Revert "Revert "2/N Rename PluginInstanceManager to PluginAction..."

Revert submission 15798157-revert-15560568-b194781951-flags-8-ZUNMWRYIZP

Reason for revert: Restoring with a fix.
Reverted Changes:
I417dd4edd:Revert "5/N Remove PluginInitializer entirely."
Ia5f864646:Revert "4/N Remove #handleWtfs from PluginInitiali...
I70f22b6a5:Revert "3/N Remove #getPrivilegedPlugins from Plug...
I07a26c9ff:Revert "2/N Rename PluginInstanceManager to Plugin...

Change-Id: I84f52b4222efc9bf406512e45a4ff523681ab77b