Had to make various other changes due to incompatibilities.
- Use the new `lit` package instead of `lit-html` or `lit-element`
- Drop `haunted` since it breaks the rules by specifying `type: module`
but then doesn't import with file extensions
- Use Sass Dart instead of node-sass (fixes#2445)
- Upgrade Karma
Still lacks inter-tab communication to update state across tabs, i.e.
when sending a 1-on-1 message in one tab, it doesn't appear in another,
because that information is not available via the websocket connection.
- Create a new `Connection` class that extends Strophe.Connection and
move related code from `converse-core.js` into this class.
- Store the session in localStorage when using a worker
- Move XEP-0156 code to connection.js
This allows us to initialize the connection without needing to know the
domain.
