Set cursor position in handwriting initiation

When handwriting is initiated for an unfocused EditText, if the stylus
down point was inside the EditText's bounds, then the EditText will
automatically set its cursor position nearest to the stylus down point
when it gains focus. If the stylus down point was outside the EditText's
bounds (within the extended handwriting bounds), then we must calculate
and set the cursor position manually.

Bug: 288461219
Test: atest HandwritingInitiatorTest
Change-Id: I62593f1ff01a7ec39c2eb6e1352d63a7f8b79f88