Enable http.url tag for server

[jcchavezs]

The http.url tag was the default record for http requests but we changed it into http.path due to privacy issues. There are a couple of request for it from @maumercado and @jeffthompson1971. Ideally we should add this option for all serverInstrumentation and should be optional.

References:

• https://github.com/openzipkin/brave/blob/e46fdc52766f21397a05857f9fb117e75be52ca6/instrumentation/http-tests/src/main/java/brave/test/http/ITHttpServer.java#L225
• https://github.com/openzipkin/brave/blob/f21d24dbfb5f57537e5cc6e5fd2e9c6290432119/instrumentation/http/src/main/java/brave/http/HttpParser.java
  -https://github.com/openzipkin/brave/blob/5a17fc018613958db00cc7b6951826e95f1b9d6c/brave/src/main/java/brave/NoopSpanCustomizer.java