There is a bug in the way the Vulkan backend handles
image respecification. Add 2 tests that expose this bug -
1. When texture format is swizzled it needs to destroy
   only the read image views
2. When texture is respecified using external images the
   FramebufferVk cache has a bug where it doesn't invalidate
   the object with the orphaned attachment

Bug: angleproject:4651
Test: angle_end2end_tests.exe --gtest_filter=ImageRespecificationTest*
Change-Id: Id564a700ea44eb4f804694613f597320ea811c07
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2246532
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>