- Serialize and deserialize completed shader source of
  program for saving out for glGetProgramBinary().
- Cleaned up some unnecessary includes in cpp files.
- Some refactoring within ProgramVk::ShaderInfo to minimize code
  duplication.
- Added ProgramVk::ShaderInfo::saveShaderSource and
  ProgramVk::ShaderInfo::loadShaderSource.
- Updated vk_caps_utils.cpp to enable getProgramBinary and add the
  GL_PROGRAM_BINARY_ANGLE program binary format. This follows the pattern
  for other backends.

Bug: angleproject:3216
Tests: dEQP-GLES3.functional.shader_api.program_binary*
       angle_end2end_tests --gtest_filter=ProgramBinaryTest*
Change-Id: I927a27aaf9aa3d7fac550819ee80d2676ec1d1be
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1683099
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>