Add leptus_handler:status/1 and use it in leptus_handler:reply/6

status/1 takes a http status name and returns the status code
Change leptus_pt to add allowed_methods that returns a list of methods

Add leptus_handler:join_http_methods/1 to join list of methods for use in 'allow' header
Add leptus_handler:is_allowed/4 to check if func exported and/or method exists in methods list
Fix tests