Add deprecation reason to GraphQL API docs

What does this MR do?

This MR adds deprecation reasons to our auto-generated GraphQL API docs.

Where a field has been deprecated, a warning icon will now display next to the field name, and the deprecation reason will now replace the description of the field.

This MR does not improve the existing deprecation reasons. We can do that in #199952 (closed).

Issue: #198571 (closed)

Screenshots

Banner

Note, since this screen cap was taken, the word "Deprecated" has been replaced with a warning icon !24331 (comment 282629757).

Field in table

latestPipeline is a deprecated field:

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 N