- Added imageSize validation checks
- Added ETC2/EAC specific validations

Change-Id: I8671b08caecb7aaff0b42d6843d31738b54d0f5a
Reviewed-on: https://swiftshader-review.googlesource.com/14088Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>