Document versions.props comment format

[ash211]

Before this PR

Expected versions.props comment format is not documented: https://github.com/palantir/gradle-consistent-versions?tab=readme-ov-file#versionsprops-lower-bounds-for-dependencies

After this PR

==COMMIT_MSG==
Document current versions.props comment format
==COMMIT_MSG==

This also adds test coverage for the documented comment formats, plus some other comment behaviors that currently exist. I'm not sure the test case in ignores_comment_on_same_line_with_no_hash() is ideal, but supporting that behavior doesn't seem to be hurting much.

Possible downsides?

None known

[changelog-app]

Generate changelog in changelog/@unreleased

What do the change types mean?

• feature: A new feature of the service.
• improvement: An incremental improvement in the functionality or operation of the service.
• fix: Remedies the incorrect behaviour of a component of the service in a backwards-compatible way.
• break: Has the potential to break consumers of this service's API, inclusive of both Palantir services
  and external consumers of the service's API (e.g. customer-written software or integrations).
• deprecation: Advertises the intention to remove service functionality without any change to the
  operation of the service itself.
• manualTask: Requires the possibility of manual intervention (running a script, eyeballing configuration,
  performing database surgery, ...) at the time of upgrade for it to succeed.
• migration: A fully automatic upgrade migration task with no engineer input required.

Note: only one type should be chosen.

How are new versions calculated?

• ❗The break and manual task changelog types will result in a major release!
• 🐛 The fix changelog type will result in a minor release in most cases, and a patch release version for patch branches. This behaviour is configurable in autorelease.
• ✨ All others will result in a minor version release.

Type

• Feature
• Improvement
• Fix
• Break
• Deprecation
• Manual task
• Migration

Description

Document current versions.props comment format

Check the box to generate changelog(s)

• Generate changelog entry

[ash211]

this seems less than ideal, but I'm not sure we gain much by making this invalid