Docs haml lint CI job

What does this MR do?

Adds job to run haml lint in docs pipelines. This detects docs changes that cause UI links to no longer be correct.

This has to run in the docs pipeline, otherwise we risk broken masters when the docs change and the frontend is not. By enabling it to true, it will also run in the static analysis job, to check that links are fine with code changes too.

Related to !35351 (merged)
Closes #208354 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team