Ask the user for debug logs when the timeline explodes
Fixes https://github.com/vector-im/riot-web/issues/9260
Workaround for https://github.com/vector-im/riot-web/issues/8593
Requires https://github.com/matrix-org/matrix-js-sdk/pull/869
We check if any dialogs are open before moving forward because we don't want to risk showing so many dialogs that the user is unable to click a button. We're also not overly concerned if the dialog being shown is irrelevant because whatever the user is doing will likely be unaffected, and we can scream in pain when they're finished.
