Describe the PR

Deprecations for #3692

Unresolved points:

• RuleContext now has the new methods of PMD 7. Maybe we should deprecate the old AbstractRule#addViolation, but the new way to do this doesn't feel great, and is also transitional anyway (asCtx(data).addViolation(node)). I think it makes sense to keep those methods around for transition. We can mark them as @DeprecatedUntil700 in PMD 7.
• @adangel Your comment talks about internalizing some members of the ant Formatter class. What about making the entire class internal in PMD 6? -> [core] Internalize some methods in Ant Formatter #3787
• Maybe other things should be deprecated, like in Renderers, though I'm inclined not to do this before we're clearer about [core] Enhancements to Renderer API #3753

I looked into the designer sources and don't think the designer needs an update.

Related issues

• [core] Analysis listeners #3692

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)