`MatrixClient.crypto` is going away, so let's switch over to `getCrypto()`.
There doesn't seem to be anything else relying on the `crypto` stub in
`mockClientMethodsCrypto()`, so let's get rid of that.
* Settings panels: avoid exceptions with rust crypto
If we are using rust crypto, `client.crypto` is undefined. We'll need to fix
these up better in future, but for now, just return early.
* Update tests