Use BGRA format for sprite

This change converts the SpriteController pixel format from RGBA
to BGRA, and changes the bitmap icon format similarly. This
conversion affects the format of the buffer that is allocated
for the SpriteController's surface, but does not result in any
user-facing changes to the appearance of the sprite. The BGRA
format is required for the cursor to be presented on the cursor
plane (instead of e.g. an overlay plane.)

To support the BGRA format, this change also introduces
ANDROID_BITMAP_FORMAT_BGRA_8888 as an anonymous enum member,
and cases are added where appropriate. It is not directly
added as a member of AndroidBitmapFormat because it is only
inteded for internal usage, and doing so in this manner prevents
it from being exposed in the Android API.

Bug: b/371003205
Flag: com.android.graphics.libgui.flags.cursor_plane_compatibility
(cherry picked from https://android-review.googlesource.com/q/commit:a22a92b690324a6d7abb52d60130e37454426940)

Change-Id: I58911d7ab40ff0637efb47a7115c84eb03a2d824