Unlike native, where in D7035 getSignedIdentityKeysBlob(...) makes a JSI call, for web we need to construct signedIdentityKeysBlob from the Redux CryptoStore. We generate getSignedIdentityKeysBlob(...) from the new getSignedIdentityKeysBlobSelector and pass it to webGetClientResponsesSelector where it will be passed to the function generated by getClientResponsesSelector (it's a lot of creating a function within a thing that creates a function within a thing that creates a function...)
Now that we have this selector, we can conveniently reuse it in TraditionalLoginForm() and SIWELoginForm(). I'll make that refactor in a subsequent diff.
Depends on D7035