This makes all the various hits done by login report the same
useful error messages and gets rid of the broken ones like printing
the http status code even if it was undefined. Also add text for
the case of overzealous browser extensions because lots of people
get bitten by it.
Fix for https://github.com/vector-im/riot-web/issues/4224
Due to the way `MatrixChat` does a state update when the `view_room` dispatch fires and a second update when `RoomViewStore` sends an update, the current event ID and room ID were becoming out of sync. The solution devised was to have the event ID managed by the `RoomViewStore` itself and do any defaulting there (for when we revisit a room that we saved scroll state for previously).
This required a few changes:
- The addition of `update_scroll_state` in `RoomViewStore` allows the `RoomView` to save scroll state for a room before swapping to another one. Previously the caching of scroll state was done in `RoomView`.
- The `view_room` dispatch now accepts an `event_id`, which dictates which event is supposed to be scrolled to in the `MessagePanel` when a new room is viewed. It also accepts `event_offset`, but currently, this isn't passed in by a dispatch in the app, but it is clobbered when loading the default position when an `event_id` isn't specified. Finally, `highlighted` was added to distinguish whether the initial event being scrolled to is also highlighted. This flag is also used by `viewRoom` in `MatrixChat` in order to decide whether to `notifyNewScreen` with the specified `event_id`.
Every file has now been manually vetted by me. Due to the extent of
the changes, I've been unable to test all scenarios to make sure this
all works. :(
Also attempt to slightly improve the feedback given when searching. There is still room for improvement - it's not totally obvious whether to display a spinner because it's quite jarring were it to replace the dd. This does mean that "No results" will flash awkardly between two queries, neither of which return any results.
