And make it actually cancel the process.
So that we can sensibly track the number completed by taking the length of it.
We now set them in the constructor
Pasting a list of addresses into the box will now pop up a dialog to confirm and show you the success / failure state of each address. It will also not die if it gets rate limited. Fixes https://github.com/vector-im/vector-web/issues/1713
David Baker