SurfaceFlinger: Add exclusion list for captureLayers.

Among other use cases, WM needs to be able to omit the IME from Task Snapshots, even while it
is on-screen.

Bug: 126614127
Test: Transaction_test.cpp#CaptureLayerExclude
Change-Id: I055d99106c9ce2ed90d64eca06961d88cbd5e2d4
2 files changed