Fix off-by-one calendar months with time zones that are greater than UTC+0 (GMT+0).
Fix https://github.com/matrix-org/matrix-public-archive/issues/77
Previously, we would calculate `lastDayOfTheMonthDate` in the local timezone because we were using the vanilla `new Date(year, month, 0)` constructor. For any timezone greater than `UTC+0` (like London UTC+1 or Korea UTC +9), this means that the date is a day-behind when we go back to UTC+0.
**Before:**
```
inputDate Fri, 29 Jul 2022 00:00:00 GMT 1659052800000
lastDayOfTheMonthDate Sat, 30 Jul 2022 23:00:00 GMT 1659222000000
lastDayOfTheMonth 30
```
**After**
```
inputDate Fri, 29 Jul 2022 00:00:00 GMT 1659052800000
lastDayOfTheMonthDate Sun, 31 Jul 2022 00:00:00 GMT 1659225600000
lastDayOfTheMonth 31
```
1. Add surrounding messages to the given messages so we have a full screen of content to make it feel lively even in quiet rooms
- As you scroll around the timeline across different days, the date changes in the URL, calendar, etc
2. Add summary item to the bottom of the timeline that explains if we couldn't find any messages in the specific day requested
- Also allows you to the jump to the next activity in the room. Adds `/:roomId/jump?ts=xxx&dir=[f|b]` to facilitate this.
- Part of https://github.com/matrix-org/matrix-public-archive/issues/46
3. Add developer options modal which is linked from the bottom of the right-panel
- Adds an option so you can debug the `IntersectionObserver` and how it's selecting the active day from the top-edge of the scroll viewport.
- In the future, this will also include a nice little visualization of the backend timing traces
Use `DisabledComposerView` instead of no composer to add message:
> You're viewing an archive of events from 2022-02-08. Use a [Matrix client](https://matrix.to/#/!HBehERstyQBxyJDLfR:my.synapse.server) to start chatting in this room.
Also refactors some of the `views` and `viewmodels` out to their own files
Eric Eastwood