Serializer for shorter YAML tags when using abstract base types

[Ataman]

This PR adds a custom serializer named CustomBaseTypeSerializer that lets coders shorten the whole !type:BaseTypeSomething into just !Something given that the base type ends in Base and their concrete implementations replace Base (and only Base) with Something. The serializer only applies when specified using the DataField attribute and includes support for most common collections.

Includes a DiagnosticAnalyzer with pre-compile time check (to prevent the serializer being applied on incorrectly named types) and unit tests for serializer and analyzer. It adds RA0045 to Diagnostics.cs for the analyzer. I couldn't find any conventions or process for requesting these and just added it for now, correct me if I got it wrong.

Rider comparison of hypothetical YAML before and after applying the serializer:

Finally, I'm not that proficient with YAML, feel free to reject this and suggest a better solution (or a better name instead of CustomBaseTypeSerializer). I'm happy to write something different if it's useful. This was also my first time writing a DiagnosticAnalyzer; it looks for typeof() expressions and checks the type param when CustomBaseTypeSerializer is in use. If there is a better approach, let me now.

[Ataman]

PR #6227 appears to use RA0045 already. Will check and update before merge if it comes to that.