mesa/st: Tie depth_clamp code into other shaders (GS and TES)

mesa/st: Tie depth_clamp code into other shaders (GS and TES)

v2: Use file scope defined depth_range_state  in common
v3: - don't use the one_shader_variant property, as this is
      not correct (Marek)
    - also use tests on available shader stages to enable
      depth_clamp lowering
v4: Don't use key.st, use st directly (Marek)

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Reviewed-by: Marek Olšák <marek.olsak@amd.com>