InputEventCompatProcessor chaining

This introduces InputEventCompatHandler, a wrapper of
InputEventCompatProcessor.
Now that each compatibility feature extends the Processor class, and the
Handler class will form a chain of reponsibility to rewrite events if
necessary.

The goal of this change is, while keeping the current
InputEventCompatProcessor interface, allowing the chain of processors.

Bug: 369865835
Test: InputEventCompatHandlerTest LetterboxScrollProcessorTest StylusButtonCompatibilityTest
Flag: EXEMPT refactor
Change-Id: I52adf5c1ed42fce6b9021d2f5571f4330c2b5fbf