EXT_clip_cull_distance extension is supported except for
some features related to EXT_tessellation_shader and
EXT_geometry_shader. Also added a few compiler tests to validate
the transformation from ESSL to GLSL for Vulkan backend.

Bug: angleproject:5458
Tests: angle_end2end_tests --gtest_filter=Clip*DistanceTest*
       angle_unittests --gtest_filter=*Clip*Distance*
Change-Id: Ie74e6b2b55112ad92ad111191d629b63506032ab
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2585987Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>