Fix Tramp problem with loooongish file names

Fix Tramp problem with loooongish file names

* lisp/net/tramp-sh.el (tramp-readlink-file-truename): New defconst.
(tramp-bundle-read-file-names): Use new %m and %q format specifiers.
(tramp-sh-handle-file-truename): Use `tramp-readlink-file-truename'.
(tramp-bundle-read-file-names, tramp-get-remote-readlink): Simplify.
(tramp-expand-script): Add format specifiers %m and %q for test
commands.  Addapt readlink call.
Reported by Stacey Marshall <stacey.marshall@gmail.com>.

(cherry picked from commit 99d70ce6c265744b21e1ffe6c034ded833917139)