anv: add VK_EXT_sampler_filter_minmax support

anv: add VK_EXT_sampler_filter_minmax support

This extension can be supported on SKL+. With this patch,
all corresponding tests (6K+) in CTS can pass. No test fails.

I verified CTS with the command below:
deqp-vk --deqp-case=dEQP-VK.pipeline.sampler.view_type.*reduce*

v2: 1) support all depth formats, not depth-only formats, 2) fix
a wrong indention (Jason).

v3: fix a few nits (Lionel).

v4: fix failures in CI: disable sampler reduction when sampler
reduction mode is not specified via this extension (Lionel).

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>