Refactor Image colorspace tests for better readability 1. Always upload color values encoded in sRGB colorspace for sampling tests and linear colorspace for rendering tests. Depending on attribute list, the test will either expect color decoded in linear space or sRGB color value as is 2. Add helper functions that determine expected output color for a given attribute list and EGLImage usage Refactor TEST and helper functions to account for the above updates Test: ImageTest*_Colorspace* Bug: angleproject:3756 Change-Id: I54ae22b2d379e6fdfa04429849de5efe9684caf4 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4643452 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: mohan maiya <m.maiya@samsung.com>