Don't assume all FP16 bitmaps are linearly encoded.

The bitmap.create() function that does not take a colorspace does
not enforce that the bitmap is linearly encoded and as such it is
possible for us to end up with FP16 bitmaps that are sRGB encoded.

Given that we want to remove that restriction (see b/120870651)
we update getColorSpace to report the actual colorSpace of the
underlying bitmap. This pulls a thread that causes a chain of
updates to various classes to ensure proper handling of the native
colorspace.

Bug: 120904891
Test: CtsUiRenderingTestCases
Change-Id: I27780aa603138b0e48f9320c2837bc53e22cdf95