fix: improve error messages of notation CLI

[Two-Hearts]

This PR improves error messages of notation sign, notation verify, notation list, and notation inspect commands. The changes include:

$ notation sign
Error: missing reference to the artifact: use `notation sign--help` to see what parameters are required

$ notation sign net-monitor:v1
Error: "net-monitor:v1": invalid reference: missing repository. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign test localhost:5000/net-monitor:v1
Error: "test": invalid reference: missing repository. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign localhost:5001/net-monitor
Error: "localhost:5001/net-monitor": invalid reference: no tag or digest. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign localhost:5001/net-monitor:
Error: "localhost:5001/net-monitor:": invalid reference: no tag or digest. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign 'localhost:5001/net-monitor:()'
Error: "localhost:5001/net-monitor:()": invalid reference: invalid tag. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign localhost:5001/net-monitor@
Error: "localhost:5001/net-monitor@": invalid reference: no tag or digest. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign localhost:5001/net-monitor@invalid
Error: "localhost:5001/net-monitor@invalid": invalid reference: invalid digest; invalid checksum digest format. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation sign --oci-layout
Error: missing reference to the artifact: use `notation sign --help` to see what parameters are required

$ notation sign --oci-layout net-monitor
Error: "net-monitor": invalid reference: missing tag or digest. Expecting <file_path>:<tag> or <file_path>@<digest>

$ notation sign --oci-layout net-monitor:
Error: "net-monitor:": invalid reference: missing tag or digest. Expecting <file_path>:<tag> or <file_path>@<digest>

$ notation sign --oci-layout net-monitor@
Error: "net-monitor@": invalid reference: missing tag or digest. Expecting <file_path>:<tag> or <file_path>@<digest>

$ notation sign --oci-layout :v1
Error: ":v1": invalid reference: missing oci-layout file path. Expecting <file_path>:<tag> or <file_path>@<digest>

$ notation sign --oci-layout '@sha256:abc'
Error: "@sha256:abc": invalid reference: missing oci-layout file path. Expecting <file_path>:<tag> or <file_path>@<digest>

$ notation verify
Error: missing reference to the artifact: use `notation verify --help` to see what parameters are required

$ notation verify net-monitor:v1
Error: "net-monitor:v1": invalid reference: missing repository. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify test localhost:5000/net-monitor:v1
Error: "test": invalid reference: missing repository. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify localhost:5001/net-monitor
Error: "localhost:5001/net-monitor": invalid reference: no tag or digest. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify localhost:5001/net-monitor:
Error: "localhost:5001/net-monitor:": invalid reference: no tag or digest. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify 'localhost:5001/net-monitor:()'
Error: "localhost:5001/net-monitor:()": invalid reference: invalid tag. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify localhost:5001/net-monitor@
Error: "localhost:5001/net-monitor@": invalid reference: no tag or digest. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify localhost:5001/net-monitor@invalid
Error: "localhost:5001/net-monitor@invalid": invalid reference: invalid digest; invalid checksum digest format. Expecting <registry>/<repository>:<tag> or <registry>/<repository>@<digest>

$ notation verify testReg/testRepo@sha256:abcd
Error: the trust store "myStore" of type "ca" does not exist. Use command 'notation cert add' to create and add trusted certificates to the trust store

$ notation verify testReg/testRepo@sha256:abcd
Error: no x509 certificates were found in trust store "myStore" of type "ca". Use command 'notation cert add' to create and add trusted certificates to the trust store

$ notation verify testReg/testRepo@sha256:abcd
Error: failed to access the trust store "myStore" of type "ca". open /home/user/.config/notation/truststore/x509/ca/myStore: permission denied

# Same pattern applies to notation list command
$ notation list ....

# Same pattern applies to notation inspect command
$ notation inspect ....

Note, this PR depends on notaryproject/notation-go#345. (On the notation CLI side, we are not displaying any individual signature error, only corresponding error messages are updated.)

notaryproject/notation-go#345 has been merged. Notation CLI dependencies are up to date.

Resolves #699
Resolves #700
Resolves #701
Resolves #808

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 59.18367% with 20 lines in your changes missing coverage. Please review.

Project coverage is 64.05%. Comparing base (31c9e84) to head (cd7e69d).
Report is 136 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/notation/verify.go	40.00%	7 Missing and 2 partials ⚠️
cmd/notation/manifest.go	0.00%	6 Missing and 1 partial ⚠️
cmd/notation/registry.go	0.00%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #810      +/-   ##
==========================================
- Coverage   64.09%   64.05%   -0.05%     
==========================================
  Files          40       40              
  Lines        2284     2323      +39     
==========================================
+ Hits         1464     1488      +24     
- Misses        698      709      +11     
- Partials      122      126       +4     

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[JeyJeyGao]

LGTM

[JeyJeyGao]

LGTM

[shizhMSFT]

LGTM

[priteshbandi]

LGTM