Support note position tracing on an image

What does this MR do?

Add a new Gitlab::Diff::PositionTracer::ImageStrategy which will be used for tracing when note is on an image. To support this, the Gitlab::Diff::PositionTracer class was refactored and the code for line based position tracing was moved to Gitlab::Diff::PositionTracer::LineStrategy class (logic didn't change).

Whenever an image gets updated/renamed/deleted, the note on it will be outdated. The system note being generated for outdated notes also links to the file in the diff instead of the entire diff.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Performance 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

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

#57793 (closed)