For an app that only draws to the swapchain, if the swapchain is
recreated with a different rotation (as done by the ANGLE perf tests
when switching from Angry Birds 2 to Candy Crush), ContextVk is not
informed, and so the new rotation is ignored.  Use the
subject-observer pattern to set the appropriate dirty bits.

Test: run_angle_perftests --gtest_filter=TracePerfTest.Run/vulkan_angry*:*vulkan_candy* --verbose --local-output
Bug: angleproject:4910
Bug: b/163126746
Change-Id: Ib5303e9c4095db1b3e736911f483589e40a73d0c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2341768
Commit-Queue: Ian Elliott <ianelliott@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Cody Northrop <cnorthrop@google.com>