[mqtt-client] A lot of various document changes

Summary:
related to T12804

- property files are now lowercase and match code names

- properties properly link to their pages

- packet names do not automatically link anymore

- TlsContext documented

- types inside handler signatures properly link to their pages

next up: better error code documentation

Reviewers: ivica

Reviewed By: ivica

Subscribers: miljen, iljazovic

Differential Revision: https://repo.mireo.local/D26155

include/async_mqtt5/impl/disconnect_op.hpp

@@ -86,6 +86,7 @@ public:
 			ec == asio::error::operation_aborted ||
 			ec == asio::error::no_recovery
 		)
+			// TODO: do we need two different errors here?
 			return complete(ec);
 
 		if (_context.terminal) {