Request utility methods / properties

[provinzkraut]

While working on the migration guide from Flask, I made a comparison table for request methods and wanted to put this out there to see if we might also want to add some of those for convenience. Specifically the headers like Range and if-match are parsed into their own datastructures, which can be helpful.

Flask	Starlite
request.cache_control	request.headers.get("cache-control")
request.content_encoding	request.headers.get("content-encoding")
request.content_length	request.headers.get("content-length")
request.content_md5	-
request.date	request.headers.get("date")
request.host	-
request.host_url	-
request.if_match	request.headers.get("if-match")
request.if_modified_since	request.headers.get("if_modified_since")
request.if_none_match	request.headers.get("if_none_match")
request.if_range	request.headers.get("if_range")
request.if_unmodified_since	request.headers.get("if_unmodified_since")
request.mimetype	-
request.mimetype_params	-
request.origin	-
request.range	request.headers.get("range")
request.referrer	request.headers.get("referrer")
request.remote_addr	-
request.remote_user	-
request.user_agent	request.headers.get("user-agent")