Support port numbers in tramp-adb

Support port numbers in tramp-adb

* net/tramp-adb.el (tramp-adb-connect-if-not-connected):
New user option.
(tramp-adb-ls-toolbox-regexp): Fix regexp in order to support file
names starting with a space.
(tramp-methods): Add `tramp-default-port' for "adb".
(tramp-adb-parse-device-names): Add traces.  Return device names
with port, if present.
(tramp-adb-handle-directory-files-and-attributes): Quote all
remote file names.
(tramp-adb-get-device): New defun.
(tramp-adb-execute-adb-command, tramp-adb-maybe-open-connection):
Use it.
(tramp-adb-maybe-open-connection): Set `tramp-current-*'
variables.  Remove checks for listed devices.