Fix gesture insets issue for IMEs

- Setting the override frame for the gesture insets sources prevents
  the insets from being calculated correctly for the IME window
- Update the set of provided insets based on the current nav mode
  so that we don't report gesture insets in button nav

Bug: 265614886
Test: Dump IME window insets for button/gesture nav
Change-Id: I22f9d09a66b50d6e2fb5002af19058657a06404d
Merged-In: I22f9d09a66b50d6e2fb5002af19058657a06404d