Handwriting delegate API changes

Per API feedback, updating handwriting delegate APIs to behave as
standard setters and getters. Removing requirement to call APIs in a
specific order, and removing side effects of setting default allowed
packages.

Bug: 266834695
Bug: 228100684
Test: atest android.view.stylus.HandwritingInitiatorTest
Test: atest android.view.inputmethod.cts.StylusHandwritingTest
Change-Id: I4ff7d53168d1fe25198a2d24faa3e45af108f989