For applications that frequently switch a texture's max level, cache
and re-use "read view" vkImageViews per max-level.

Test: NBA 2K20
Test: angle_deqp_gles3_tests --gtest_filter=dEQP.GLES3/functional_texture_mipmap_*_max_level_* --use-angle=vulkan
Bug: b/161993151
Change-Id: I9a6a81d5234196040bc6c264ec627a073ba73293
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2321370
Commit-Queue: Ian Elliott <ianelliott@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>