this also makes it work again, as the VerificationPanel doens't
know how to deal with requests that are already in PHASE_STARTED,
which was breaking verifying your own devices.
To store toast. Rather than them being stored in the state of the
ToastContainer component, they now have a dedicated store. This mostly
fixes problems involving showing toasts when the app loaded because
we would otherwise have a race condition where something tries to
show a toast before the ToastContainer is mounted.
Verification with cross-signing may requiring asking for your secret storage
passphrase, which is displayed in it's own modal on top of flows. For now while
verification takes in modals also, mark the verification ones as static so they
don't lose state when secret storage appears on top mid-flow.
this uses a verification requests as emitted by the js-sdk with
the `crypto.verification.request` rather than a verifier as emitted
by `crypto.verification.start` as this works for both to_device and
timeline events with the changes made in the js-sdk pr.
