jewel: Use by-name partitions in fstab

* Also change encryption to use the 'extra' partition.
* Also remove recovery specific fstab.

Change-Id: I68ed1aaa1d8b0a74b8eb16093d2f2a028b687ccb
jewel: default to MTP USB mode

You can't default to ADB since user is required to enable USB debugging
before adb kicks in. UMS was deprecated to help save users from
themselves (unclean unmounts and apps left wondering what happened to
their storage volume). We should at least default to MTP, even if users
will opt to change this later.

Change-Id: Idd1dc485c9cceeb1ff44a60d9bfd0b25a22a4046
jewel: Create firmware symlinks at build time

Change-Id: Ib6deca8b04030a4fdb354a2a9b5c61d3787bc7a2