Add `shellcheck` to CI

[tenzen-y]

/kind feature

Describe the solution you'd like
[A clear and concise description of what you want to happen.]

Add shellcheck to verify all shell scripts in this repository.

Ref: #1731 (comment)

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

[anencore94]

Absolutely agree :)
also, I think add yamllint on CI could make yaml files more readable for newbies.
(https://github.com/adrienverge/yamllint)

Furthermore, I'm not sure since I didn't used this actually, but just try examining kube-linter would be nice too for the same reason. (https://github.com/stackrox/kube-linter)

[tenzen-y]

It sounds good to me, thanks! @anencore94

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tenzen-y]

/lifecycle frozen

[tenzen-y]

I take this issue.
/assign

[gaocegege]

Thanks for your contribution! 🎉 👍

[johnugeorge]

/lgtm

@gaocegege Can you review this as well?

[tenzen-y]

Thanks, @johnugeorge!
#1857 resolves this issue.