renderer: add underlying support for 16bit textures on gles
renderer: move UploadYV12Texture to same location as in GLES renderer

Simplifies diffing
renderer: match GLES UploadYV12Texture structure with GL version
renderer: calculate source rect on upload GLES:EGL/CVRef/MediaCodec
fixup! renderer: calculate source rect on upload GLES:EGL/CVRef/MediaCodec
renderer: factor out logic for upgrading GL format to 16bit
fixup! renderer: add underlying support for 16bit textures on gles
Merge pull request #3751 from elupus/gles

Minor gles renderer cleanup and fixes