bugfix: flaky test case in cli_start_test.go

[fuweid]

Ⅰ. Describe what this PR did

When we create container, we should have ability to open STDIN even
though we don't attach it yet. Otherwise, the pouch start command's
attach with stdin will not work well.

Therefore, pouch create need to support -i flag to keep STDIN open.
And in order to make the case easy to read, we can use StdinPipe
instead of github.com/kr/pty which we don't need any more.

Signed-off-by: Wei Fu fuweid89@gmail.com

Ⅱ. Does this pull request fix one issue?

NONE

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

no need.

Ⅳ. Describe how to verify it

check it manually and use test case to verify.

if we don't keep stdin open, the start will return immediately even though with -a -i.

# first, create container without openStdin
$ sudo pouch create --name t1 ubuntu cat

# start it
$ pouch start -a -i t1

if we keep stdin open, it will act like echo server.

➜  test git:(bugfix_container_io) sudo pouch create --name t2 -i ubuntu cat
106adbedb380377a76b814f221fa503bdb6211fbfcc55f68ca8ea2e9d467eeec
➜  test git:(bugfix_container_io) sudo pouch start -a -i t2
skdfj
skdfj
sfkj
sfkj

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Merging #2665 into master will increase coverage by 1.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2665      +/-   ##
==========================================
+ Coverage    68.6%   69.62%   +1.02%     
==========================================
  Files         281      281              
  Lines       18699    18699              
==========================================
+ Hits        12828    13020     +192     
+ Misses       4399     4230     -169     
+ Partials     1472     1449      -23

Flag	Coverage Δ
#criv1alpha1test	31.69% <ø> (-0.19%)	⬇️
#criv1alpha2test	36.04% <ø> (-0.02%)	⬇️
#integrationtest	42.12% <ø> (-0.03%)	⬇️
#nodee2etest	32.53% <ø> (?)
#unittest	27.23% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pkg/streams/utils.go	82.14% <0%> (-9.53%)	⬇️
cri/v1alpha1/cri.go	59.43% <0%> (-0.67%)	⬇️
daemon/mgr/container.go	59.22% <0%> (+0.42%)	⬆️
ctrd/image.go	78.99% <0%> (+0.91%)	⬆️
cri/v1alpha2/cri_utils.go	88.44% <0%> (+1.78%)	⬆️
cri/stream/remotecommand/httpstream.go	46.63% <0%> (+2.59%)	⬆️
ctrd/container.go	58.49% <0%> (+2.76%)	⬆️
ctrd/watch.go	80.28% <0%> (+2.81%)	⬆️
daemon/mgr/spec_linux.go	79.73% <0%> (+2.99%)	⬆️
daemon/logger/jsonfile/encode.go	81.52% <0%> (+3.26%)	⬆️
... and 7 more

[rudyfly]

LGTM, wait ci pass