Previously we were missing the client only prefix and we were allowing .'s and -'s

in the vendor field. I've updated the regex to support this and split the key

into all of it's parts; the key, client only prefix, vendor, and key_name. Right

now we only use the full key, but we may need to change the way we represent

tags in memory to accomidate all of these fields.
This also means we are telling the server we support the TAGMSG command which

we do not yet implement, but that should be fine for now.

Ran the unit tests

Connected to a local ergo instance and verified the capability was ack'd.

Connected to libera and discovered they don't currently support message tags.