Add support for message tags

[Half-Shot]

This enables the bridge to start parsing out messages tags from compliant IRC servers as per https://ircv3.net/specs/extensions/message-tags. It for the moment is very unspecified so all tags are returned as a Map to the client, to then use as it sees fit.

[progval]

What's the reason for the supportsMessageTags option? Why not unconditionally allow message tags?
Also note that you may get message tags if you negotiate the account-tag or server-time capabilities, even without the message-tags capability (because they both predate the message-tags spec)

This is missing support for unescaping tag values.

for the moment is very unspecified so all tags are returned as a Map to the client, to then use as it sees fit.

that's the right way to do it in a library IMO

[Half-Shot]

Escaping should now be working & tested.

As far as allowing support, it felt pretty sensible to check for the serverside support before parsing to ensure they support the exact spec we've been working against. Can probably also enable it with account tag or server time caps. I think any sever that wants to offer support for message tags should be broadcasting this though.

[progval]

s/escape/unescape/ in your last commit message, and you might want to add a test for that.

And having @tags but no :prefix is valid, it shouldn't raise "No prefix on message" (and the regexp should be updated to support it)

The rest looks good to me (though not tested myself)

[Half-Shot]

s/escape/unescape/ in your last commit message, and you might want to add a test for that.

And having @tags but no :prefix is valid, it shouldn't raise "No prefix on message" (and the regexp should be updated to support it)

Failing to spot that in the spec for server sent messages, is there a reference somewhere?

[progval]

Servers MAY include a source on any message, and MAY leave a source off of any message. Clients MUST be able to process any given message the same way whether it contains a source or does not contain one.

-- https://modern.ircdocs.horse/#source

[Half-Shot]

Started working on support for prefix-less messages, but didn't fully get there. Will come back to this.