Upgrade to Excalidraw v0.16.1
======
[CHANGELOG](https://github.com/excalidraw/excalidraw/blob/master/src/packages/excalidraw/CHANGELOG.md)

### Schema
- I have confirmed that there are no schema changes in the changelog
- I have created a whiteboard with the old version and another with the new version and looks like the property `isFrameName: boolean` of the elements `"type": "text",` is now missing:
- I have digged a bit into this, looks like there was a new feature called frames and that property was added but then removed by [this commit](https://github.com/excalidraw/excalidraw/commit/b57b3b573da874f7527589c10632ec936c1962d2#diff-205831ba144cafaba7bdcaab8e1affeb0eb97a4da50714294f73d307347e5d8e) and I don't see any mention to it, so I think we can safely ignore this prop

### Test
From here, I have installed @excalidraw original package v0.16.1 locally to test it.

### API and Refactors required.
- None of the breaking changes in the changelog affect us.
- They are using VITE now, so maybe (probably) it's going to be easier to import some missing classes that we had to copy paste from excalidraw-app to create WhiteboardRts functionality
- They say they have implemented zoomToFit feature and very small refactor is needed from our side (instead of calling our custom `zoomToFit()` function, we have to call `scrollToContent(undefined, { fitToContent: true });`

### UI
- They have added ZoomToFit through the API but they haven't added our custom button, we may miss that if we use directly @excalidraw/excalidraw: 

### Behaviour
- I don't know why but the grid is behaving a bit weirdly. It has lost the grid completely until I use the freehand tool, then it appears.
Looks like a bug, when I drag something freehand, the grid is still disabled, but when I release the mouse the grid appears.

### Implications / Benefits
- Switch to VITE
- Move excalidraw-app outside src - cleaner code
- Keep our fork, because the zoomToFit button is a good feature and not hard to maintain at all
- Need to investigate what happens with the grid - The problem is ours
- I have downloaded a fresh copy from the @excalidraw/excalidraw repo, checkout v16.0.1, npm i, npm start and modified the file ./excalidraw-app/index.tsx line 699 add `gridModeEnabled` and I can see the grid.
- The [list of new fetaures and fixes](https://github.com/excalidraw/excalidraw/blob/master/src/packages/excalidraw/CHANGELOG.md#excalidraw-library-1) has some nice things