feat(lift-actor)!: support scala 3

[farmdawgnation]

Support cross build for scala3 for lift-actor. Specifically:

• Drop Java interop support
  • Some changes in the Scala 3 compiler seem to make it impossible to inherit SpecializedLiftActor via LiftActor in Java code.
• Fixed a tailrec issue in Scala 3

[Copilot]

Pull Request Overview

This PR adds Scala 3 support to the lift-actor module by removing Java interoperability features and fixing a tail recursion issue. The changes are part of a breaking change to enable cross-compilation with Scala 3.

• Removes Java interop classes and annotations that are incompatible with Scala 3
• Fixes tail recursion implementation in LAFuture.get method
• Removes Java-based test files and related Scala test cases

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
web/webkit/src/main/scala/net/liftweb/http/CometActor.scala	Removes Java interop classes LiftActorJWithListenerManager, CometActorJ, and CometActorJWithCometListener
core/actor/src/test/scala/net/liftweb/actor/ActorSpec.scala	Removes Java actor test case
core/actor/src/test/java/net/liftweb/actor/MyJavaActor.java	Deletes Java test actor implementation
core/actor/src/main/scala/net/liftweb/actor/LiftActor.scala	Removes Java interop support including LiftActorJ class and reflection-based dispatch
core/actor/src/main/scala/net/liftweb/actor/LAFuture.scala	Fixes tail recursion issue by restructuring the get method
core/actor/src/main/java/net/liftweb/actor/JavaActorBase.java	Deletes Java annotation class for actor message handling

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