Allow using multiple strategies simultaneously to make an app more robust

[dragonman225]

Since strategies are usually transparent to an app, it might be a good idea to use multiple strategies simultaneously. This way, if one strategy fails completely — such as when an update changes the protocol of the infrastructure software used by all providers of a strategy, or when all providers of a strategy are blocked by a firewall — we can still maintain functionality using other working strategies.

Instead of asking users to manually switch strategies (which could be confusing if they choose different ones and struggle to connect), or running two separate strategies with two rooms to manage (where we might need to ignore duplicate media streams and data messages from different rooms), it would be better if the room handle multiple strategies. This approach would be similar to how the room currently manages multiple relay servers for a single strategy.

[rogersanick]

Great idea! I have experimented with several strategies to see which is best. Composeable strategies would be incredible.