Rename WIP page to Drafts and clean up

What does this MR do?

This merge request starts the heavy lifting of removing all traces of WIP from our documentation, as requested in #231502 (closed). It does a LOT of things.

• Renames the page from user/project/merge_requests/work_in_progress_merge_requests.md to user/project/merge_requests/drafts.md

• Adds a redirect

• Revamps page text

• Moves WIP information to a deprecation warning box

• Takes out everything WIP possible

• Rewrites most of the page for clarity

• Renames subheadings to more closely follow CTRT expectations and the style guide

• Updates crosslinks

• Updates images to new versions and removes the old images

• Related to #231502 (closed) where the request was made

• Related to #32692 (closed)

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