Add Google Drive support to Tramp

Add Google Drive support to Tramp

* doc/misc/tramp.texi: Add `gdrive' method.

* doc/misc/trampver.texi:
* lisp/net/trampver.el: Change version to "2.3.1-pre".

* etc/NEWS: Add Tramp connection method "gdrive".

* lisp/net/tramp-gvfs.el (tramp-gvfs-methods) <gdrive>: Add.
(tramp-default-user-alist, tramp-default-host-alist): Add rule
for "gdrive".
(tramp-gvfs-file-attributes): Add "name", remove "standard::icon".
(tramp-gvfs-file-attributes-with-gvfs-ls-regexp): Simplify regexp.
(tramp-gvfs-get-directory-attributes): Improve loop.  Use
"standard::display-name" as file name, if available.
(tramp-gvfs-handle-file-name-all-completions): Simplify.
(tramp-gvfs-url-file-name, tramp-gvfs-handler-mounted-unmounted)
(tramp-gvfs-connection-mounted-p, tramp-gvfs-mount-spec):
Map between "gdrive" and "google-drive".

* lisp/net/tramp.el (tramp-call-process): Do not signal error.

* test/lisp/net/tramp-tests.el (tramp--instrument-test-case):
Do not enable `tramp-message-show-message'.
(tramp-test13-make-directory, tramp-test14-delete-directory):
Do not specify error type.