Configurable username format for webhook relays

[austinhuang0131]

Originally posted at https://geekdom.social/@bigolifacks/112859769835968061 (not me); the concerning code is

discord/portal.go

Lines 1436 to 1441 in 035f2a4

	func (portal *Portal) getRelayUserMeta(sender *User) (name, avatarURL string) {
	member := portal.bridge.StateStore.GetMember(portal.MXID, sender.MXID)
	name = member.Displayname
	if name == "" {
	name = sender.MXID.String()
	}

so eg. allows the bridge to always include MXID in the webhook display name.

[tulir]

Making it configurable doesn't really solve anything. I'll probably include proper disambiguation in megabridge, but I couldn't find any Go libraries for UTS #39 confusable detection, so will need to write one first

[Raymo111]

@tulir Making it configurable solves the problem of people not knowing where the webhook is bridging from (enables appending something like | from CC Chat. I think having it would be a good feature even without the megabridge disambig.