Update component to WMShell

Currently, bugs in non flicker WMShell tests are filled in the flicker component instead of WMShell.

Add a fallback owners file to flicker folder so that flicker bugs still to go the flicker component unless explicitly configured in the child directories

Test: N/A
Change-Id: I134fbf89f2a80bda035084c7a6c5ca85249292b6