installd has moved on to Binder; goodbye socket!

After a series of recent commits, installd has fully migrated over
to Binder, and all socket-based communication has been removed.

Test: builds, boots, apps install fine, pre-OTA dexopt works
Bug: 13758960, 30944031
Change-Id: Ia67b6260de58240d057c99b1bbd782b44376dfb5