Support standard streamid syntax with unit tests

[gpmidi]

An updated version of #39 with unit tests. Also added support for passing on the username to the upstream AAA. Plus a few random non-bug fixes I ran across while I was at it.

[gpmidi]

@iSchluff I'm working on unit tests for this and noticed that the TestServerImpl_GetStatistics test fails. The tl;dr is that it's old vs new format. I can either update the test to use the SRT defined spec or figure out a way to base the answer on what was sent to the server in the first place. Thoughts?

For now I've just reverted the output to the pre-change version just so the behavior doesn't change on dependent apps.

=== RUN   TestServerImpl_GetStatistics
    server_test.go:52: Invalid stream statistics: got {s1 srt://testserver.de:1337?streamid=#!::m=request,r=s1 2 2024-11-25 14:48:26.374969306 -0500 EST m=+0.000745398}, expected {s1 srt://testserver.de:1337?streamid=play/s1 2 2024-11-25 14:48:26.374969306 -0500 EST m=+0.000745398}
--- FAIL: TestServerImpl_GetStatistics (0.00s)

[iSchluff]

I'm not super attached to the url returned in GetStatistics. The main goal is having something that ffmpeg understands. So if the new format still works with ffplay I am fine with changing the result.

[gpmidi]

@iSchluff Thanks! I'll test it locally with ffmpeg to double check and report back.

[gpmidi]

ffplay works fine with the new url format

[gpmidi]

@iSchluff Ready for review. Can close out #39 when this is merged :)

[gpmidi]

@iSchluff Any chance on a PR review?