Allow non-IRC line delimiters with ERC test server

Allow non-IRC line delimiters with ERC test server

* test/lisp/erc/resources/erc-d/erc-d.el (erc-d-server-fqdn,
erc-d--initialize-client, erc-d--log, erc-d--send, erc-d--filter,
erc-d-run): Add new variable and use it.  Also optionally accept
keyword arguments in `erc-d-run'.

* test/lisp/erc/resources/erc-d/erc-d-tests.el
(erc-d-run-direct-foreign-protocol): Add test demoing newline-only
line-wise protocol.

* test/lisp/erc/resources/erc-d/resources/foreign.eld: New file.