dEQP tests suggest that passing a value other than GL_FALSE or GL_TRUE
to ProgramParameteri generates INVALID_VALUE. The code is also
refactored so that the implementation of ProgramParameteri is in the
Context object.

BUG=angleproject:1101
TEST=dEQP-GLES3.functional.negative_api.shader.program_parameteri

Change-Id: I432d19fb574e58a7e0059189ab5b1863de029cdc
Reviewed-on: https://chromium-review.googlesource.com/336163Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>