Add test module target on Makefile

[khanhtc1202]

What this PR does / why we need it:

Add test-mod target on Makefile in case run test for specific modules/dirs.
Test with DIR=pkg/app/api make test-mod command.

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

NONE

[pipecd-bot]

Code coverage for golang is 33.66%. This pull request does not change code coverage.

[nghialv]

Not sure why do we need this?
Just running make test and Bazel automatically detects what should be tested.

[khanhtc1202]

Not sure why do we need this?
Just running make test and Bazel automatically detects what should be tested.

not sure what when wrong but on my local, make test usually run all the tests on a newly opened terminal session 🤔 So I thought at least specific which dirs/modules of tests should be run bring better development experience.

[nghialv]

/approve

[pipecd-bot]

This pull request is APPROVED by nghialv.

Approvers can cancel the approval by writing /approve cancel in a comment. Any additional commits also will change this pull request to be not-approved.

[khanhtc1202]

@nghialv I somehow figured out what happened on my local, rebuild/rerun test occurred on switching between editor's terminal ( Vscode ) and os's terminal 👀
did it occur on your end 👀 ( update .bazelrc may resolve this issue )
ref: bazelbuild/intellij#789

[nghialv]

@khanhtc1202 lol. It worked perfectly for me. I am using the same zsh for both terminal and VScode.