[CS] Remove memorisation of domains and config of call/mixer domains from XMPP connection

Rely on domain from command object to specify the target domain, falling back to the service root domain
[CS] Include command/event domain in attributes

This makes it comparable and show up in inspect
[FEATURE] Allow specifying a command's domain as an option when writing a command via XMPP
[BUGFIX] Refs should deal with full JIDs (and URIs including xmpp: scheme)
[BUGFIX] Dial commands should set call ID and domain from full JID Ref
[FEATURE] Allow more flexible Ref URI schemes

Expose transport in events and responses to Dial.
[BUGFIX] Accept Ref URIs which are just plain strings
[CS] Deal with component references by URI
Merge branch 'develop' into feature/rayo_full_uri
Merge branch 'feature/rayo_full_uri' into develop