MEDIUM: logs: Add HTTP request-line log format directives

MEDIUM: logs: Add HTTP request-line log format directives

This commit adds 4 new log format variables that parse the
HTTP Request-Line for more specific logging than "%r" provides.

For example, we can parse the following HTTP Request-Line with
these new variables:

  "GET /foo?bar=baz HTTP/1.1"

- %HM: HTTP Method ("GET")
- %HV: HTTP Version ("HTTP/1.1")
- %HU: HTTP Request-URI ("/foo?bar=baz")
- %HP: HTTP Request-URI without query string ("/foo")