Lift restrictions on `tramp-androidsu's app data access

Lift restrictions on `tramp-androidsu's app data access

* lisp/net/tramp-adb.el (tramp-adb-handle-copy-file): Remove
code now unnecessary.

* lisp/net/tramp-androidsu.el
(tramp-androidsu-mount-global-namespace): New user option.
(tramp-androidsu-su-mm-supported): New variable.
(tramp-androidsu-maybe-open-connection): Detect whether su
supports the -mm option, and provide it if so.
(tramp-androidsu-adb-handle-copy-file)
(tramp-androidsu-adb-handle-rename-file): Delete functions.
(tramp-androidsu-sh-handle-copy-file)
(tramp-androidsu-sh-handle-rename-file): New functions.
(tramp-androidsu-file-name-handler-alist): Switch to tramp-sh's
copy and rename handlers.

(cherry picked from commit f1db8cf9a0595f7db29b548b38ce98196f36e09b)