D3D: Remove more usages of program instead of executable Only usage of getProgram() and getLinkedProgram() in the d3d backend remains for multidraw, which will be fixed separately as it involves setting uniforms (currently done through the program). Bug: angleproject:8297 Change-Id: I48b3ec66837888c8ebf58f43a6d8a2f483dd4659 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4846954 Reviewed-by: Shahbaz Youssefi <syoussefi@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>