auth-source-pass: Take care of matching hosts when port is provided

auth-source-pass: Take care of matching hosts when port is provided

* lisp/auth-source-pass.el (auth-source-pass--find-match): Add PORT
parameter and reorganize code by extracting `find-match-unambiguous'.
(auth-source-pass--find-match-unambiguous): New function.
(auth-source-pass--build-result): Fix the call to `find-match'.
(auth-source-pass--hostname, auth-source-pass--hostname-with-user,
auth-source-pass--user): Remove functions.
* test/lisp/auth-source-pass-tests.el: Fix the calls to `find-match'.
(auth-source-pass-find-host-without-port) Add corresponding test.