If we have account data in local storage but nothing in the crypto store, it
generally means the browser has evicted IndexedDB out from under us. This adds a
modal to explain the situation and offer to completely clear storage to get
things back to normal.
Fixes https://github.com/vector-im/riot-web/issues/9109
We moved off to our own fork of velocity many moons ago to fix
a memory leak bug when velocity was being barely maintained. They
have now merged the bugfix, so go back to mainline.
For the React SDK, we did not commit npm lock files, so there is no correct copy
to import from. For this repo, I created a fresh yarn lock file using yarn
install.
