A piece of code shared with d3d was used to implement this feature.
However, we store the uniform data transposed and row-major in d3d to
accomodate the fact that matrix indexing in HLSL is the opposite of GLSL
(mat[row][col] in HLSL as opposed to mat[col][row] in GLSL).

There were two functions that copied the source matrix fields either as
column-major or source-major (corresponding to `transpose` false or true
respectively in glUniformMatrix*) into a row-major destination.  These
functions are refactored into one, which copies from any-major source to
any-major destination.  The HLSL backend uses the "to row-major" variant
and the Vulkan backend uses the "to column-major" variant.

Bug: angleproject:3198
Change-Id: I7254da4fbe6916af78c5906abcb82ca01674ab9f
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1607541
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>