refactor: command after sync serialization

[bsbds]

Described in: #420

Based on: #421

Please briefly answer these questions:

• what problem are you trying to solve? (or if there's no problem, what's the motivation for this change?)

• what changes does this pull request make?

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc)

[codecov]

Codecov Report

Patch coverage: 51.11% and project coverage change: +0.11% 🎉

Comparison is base (24a5f1f) 54.02% compared to head (7e2053b) 54.14%.
Report is 2 commits behind head on master.

❗ Current head 7e2053b differs from pull request most recent head b30fa33. Consider uploading reports for the commit b30fa33 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #422      +/-   ##
==========================================
+ Coverage   54.02%   54.14%   +0.11%     
==========================================
  Files         101      101              
  Lines       16630    16739     +109     
  Branches    16630    16739     +109     
==========================================
+ Hits         8985     9063      +78     
- Misses       7101     7124      +23     
- Partials      544      552       +8     

Files Changed	Coverage Δ
curp-external-api/src/cmd.rs	30.23% <ø> (ø)
curp/src/client.rs	16.76% <0.00%> (-0.20%)	⬇️
curp/src/lib.rs	100.00% <ø> (ø)
curp/src/rpc/connect.rs	35.84% <ø> (ø)
curp/src/rpc/mod.rs	22.03% <0.00%> (-1.82%)	⬇️
curp/src/server/curp_node.rs	23.70% <0.00%> (ø)
xlineapi/src/lib.rs	71.69% <ø> (ø)
curp-test-utils/src/test_cmd.rs	80.53% <22.22%> (-1.92%)	⬇️
curp/src/error.rs	58.19% <66.66%> (+23.58%)	⬆️
xline/src/server/command.rs	70.45% <90.62%> (+0.89%)	⬆️
... and 2 more

... and 2 files with indirect coverage changes

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[LingKa28]

The files generated from .proto files for Rust are organized into workspaces, but if my generated files are all in one project. The command.proto and error.proto files have the same name, and the Empty struct is duplicated. At runtime, the project will error due to the duplication between the two files.

proto: file "error.proto" is already registered
proto: file "error.proto" has a name conflict over errorpb.Empty
proto: message errorpb.Empty is already registered
proto: file "command.proto" is already registered

But, this issue can be ignored by setting an environment variable.

GOLANG_PROTOBUF_REGISTRATION_CONFLICT="ignore"

[bsbds]

The files generated from .proto files for Rust are organized into workspaces, but if my generated files are all in one project. The command.proto and error.proto files have the same name, and the Empty struct is duplicated. At runtime, the project will error due to the duplication between the two files.

proto: file "error.proto" is already registered
proto: file "error.proto" has a name conflict over errorpb.Empty
proto: message errorpb.Empty is already registered
proto: file "command.proto" is already registered

But, this issue can be ignored by setting an environment variable.

GOLANG_PROTOBUF_REGISTRATION_CONFLICT="ignore"

I replaced the two Empty types with google.protobuf.Empty, now it should be consistent.

[Phoenix500526]

Please squash commits in this PR, some of them are too granular.