Introduce linting for actions workflow files

[jmhbnz]

What would you like to be added?

This is a sub issue under #15951.

Our etcd github actions workflows currently fail a number of very basic yamllint tests, examples that are worth fixing are below:

./.github/workflows/contrib.yaml
  1:1       warning  missing document start "---"  (document-start)
  11:5      error    wrong indentation: expected 6 but found 4  

./.github/workflows/scorecards.yml
  1:1       warning  missing document start "---"  (document-start)
  8:16      error    too many spaces inside brackets  (brackets)
  8:23      error    too many spaces inside brackets  (brackets)
  49:1      error    trailing spaces  (trailing-spaces)

We should ignore the follow warnings:

Warning	Reason
Line too long	Usually problematic to try and address.
truthy value should be one of [false, true]	Yamllint doesn’t understand the concept of on: for github actions files.
too few spaces before comment	This generally refers to the comments added automatically by dependabot for ci actions versions so we should leave these.

While the existing errors should be fixed we should also consider introducing a minimal yamllint configuration and potentially make target to ensure new errors don't creep in over time and we maintain best practices.

Why is this needed?

Enforce best practices for yaml files.

[tao12345666333]

Please assign to me, thanks

[jmhbnz]

All yours @tao12345666333, thanks for offering to help!

A couple quick notes on your approach for this:

• Consider doing an initial pull request or multiple smaller pull requests just to fix existing lint issues, then doing a follow-up pull request for the implementation of automated lint checks as part of the static analysis github actions workflow.
• When introducing the automated checking please do so via new Makefile make verify ... and make fix ... targets.

Feel free to reply here or message me on the Kubernetes slack if any questions pop up 🙂

[jmhbnz]

Closing as both sub tasks have been completed, thanks @tao12345666333 🚀