Yank all the code to install OTA packages out of the recovery binary
itself. Now packages are installed by a binary included in the
package (run as a child of recovery), so we can make improvements in
the installation process without waiting for a new release to use
them.
Amend (aka the recovery command language) had a half-implemented
scheme of limiting which commands OTA packages were allowed to
execute. It's not clear what this was ever supposed to be good for.
Remove it.
