Add new Tramp method "flatpak"

* doc/misc/tramp.texi (Inline methods): Add flatpak.

* etc/NEWS: Add new Tramp method "flatpak".  Fix typos.

* lisp/net/tramp-container.el (tramp-flatpak-program): New defcustom.
(tramp-flatpak-method): New defconst.
(tramp-flatpak--completion-function): New defun.  Set it for "flatpak".
(tramp-methods) <flatpak>: Add.
(tramp-container-connection-local-default-flatpak-variables):
New defconst.  Set respective connection-local variables.

1 files changed, 10 insertions, 0 deletions

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 65892f8621e..247d718b59a 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -938,6 +938,16 @@ be used.
 
 This method does not support user names.
 
+@item @option{flatpak}
+@cindex method @option{flatpak}
+@cindex @option{flatpak} method
+
+Integration of Flatpak sandboxes.  The host name may be either an
+application ID, a sandbox instance ID, or a PID, as returned by
+@samp{flatpak ps}.
+
+This method does not support user names.
+
 @end table