Handle also port and domain in Tramp proxy definitions

Handle also port and domain in Tramp proxy definitions

* doc/misc/tramp.texi (Multi-hops): Exclude ports and domains from
pattern expansion.

* lisp/net/tramp-cmds.el (tramp-cleanup-all-connections):
Remove ad-hoc proxies.

* lisp/net/tramp-sh.el (tramp-compute-multi-hops): Handle also
port and domain in the proxy.  Propertize ad-hoc proxies.

* lisp/net/tramp.el (tramp-default-proxies-alist): Adapt docstring.

* test/lisp/net/tramp-tests.el (tramp-test02-file-name-dissect)
(tramp-test02-file-name-dissect-simplified)
(tramp-test02-file-name-dissect-separate): Extend tests.