Test the http redirection at the request level even if it's not
used anymore, so far.

* bzrlib/transport/http/_urllib2_wrappers.py
(HTTPRedirectHandler.http_error_302): Renamed from http_error_30x.
(HTTPRedirectHandler.http_error_301): Deleted. Finally, that's the
easiest way to fix bug #88780 :) In retrospect, that code was a
first attempt to handle this whole redirection handling by
providing the final target to the first request. This is not
needed anymore.

* bzrlib/tests/test_http.py:
(RedirectedRequest, TestHTTPSilentRedirections_urllib): Test the
_urllib2_wrappers redirection at the request level.

* bzrlib/tests/HTTPTestUtil.py:
(RedirectRequestHandler.parse_request): Delegate the redirection
handling to the test_case_server.
(HTTPServerRedirecting.is_redirected): Handle redirections by
searching a matching directive.
(HTTPServerRedirecting.redirect_to): Redefined to use the nre
redirections definitions.