Add support for line bridge

[NCLI]

There is now a bridge for the LINE messaging client, which is very popular in east Asia. It would be nice to have support for it.

[spantaleev]

All our bridges are user-contributed, by people who need to use them or otherwise have interest in the bridge.

It'd be nice to add LINE support and if someone is up to the task of adding it, I'd be happy to support them in doing such a PR.

Normally, new bridges aren't too difficult to add support for. One needs to copy one of our existing bridge roles and modify it.

However, for the LINE puppeteer bridge, it seems like the setup instructions are somewhat more complex (multiple services are involved - the bridge itself and the Puppeteer module; one needs to download some Chrome extension too; etc), so maybe it's more difficult to add.

That said, the Signal bridge (roles/matrix-bridge-mautrix-signal) also manages multiple systemd services, so one can take inspiration from there.

[extremelyonline]

Am also interested in adding support to this! Will try adding it