Avoid Spell Checker initialization during anim

TextView initializes the spell checker when the view is attached to a
window, making a couple of IPCs.
These IPCs can contribute to jank, so we should avoid them if we can.

This CL delays the initialization until the edit text actually becomes
visible.

Test: perfetto trace
Test: atest RemoteInputViewTest
Fixes: 191953960
Change-Id: I27820986ec925f5edbf7e26f6b8f7311f6d2f467