Indicate progress of slow E2EE startup

When a Hookshot bot account enters an encrypted room for the first time, it takes a few seconds for Hookshot to set up that bot's crypto-enabled device (via the bot-sdk).

Of course the ideal solution is to speed up the crypto initialization, but until then it would be nice to at least have some sort of visual indication that Hookshot hasn't frozen/crashed, but is instead setting itself up.

One idea I'm particularly fond if is for a bot account to send a typing notification while its crypto is being set up.