shader: Change the internal uniforms to uniform blocks

Allows to only reduce the max number of uniform blocks by 1 instead of
slightly reducing the number of uniforms.

Signed-off-by: Corentin Noël <corentin.noel@collabora.com>
Part-of: <!815>
17 jobs for !815 with tintou/uniform-blocks in 19 minutes and 9 seconds (queued for 2 seconds)
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