[Impeller] Reland: Correctly compute UVs in texture fill (#43093) Resolves https://github.com/flutter/flutter/issues/128353. Reverts https://github.com/flutter/engine/pull/43087. Reland without the kDecal usage -- we don't need it after the last iteration of fixes. https://dart.googlesource.com/external/github.com/flutter/engine/+/21a7c76d6f13f47e05d989d7f282168bb14348a2