Allow users to set document name and use it for exporting / saving (#2685)

Adds the ability to change document names in the top center part of the
UI. This mostly brings back the functionality we already had in the
past.

This is basically a port of what @SomeHats did a while back. I changed
the dropdown options and removed some of the things (we are not dealing
with network requests directly so some of that logic did not apply any
longer). We did have autosave back then, not sure if we want to bring
that back?

Changes the `exportAs` api, thus braking.

### Change Type

- [ ] `patch` — Bug fix
- [ ] `minor` — New feature
- [x] `major` — Breaking change
- [ ] `dependencies` — Changes to package dependencies[^1]
- [ ] `documentation` — Changes to the documentation only[^2]
- [ ] `tests` — Changes to any test code only[^2]
- [ ] `internal` — Any other changes that don't affect the published
package[^2]
- [ ] I don't know

[^1]: publishes a `patch` release, for devDependencies use `internal`
[^2]: will not publish a new version

### Test Plan

1. Top center should now show a new UI element. It has a dropdown with a
few actions.
2. Double clicking the name should also start editing it.
3. The name should also be respected when exporting things. Not if you
select some shapes or a frame. In that case we still use the old names.
But if you don't have anything selected and then export / save a project
it should have the document name.

- [ ] Unit Tests
- [ ] End to end tests

### Release Notes

- Allow users to name their documents.

packages/editor/src/lib/utils/debug-flags.ts

@@ -52,6 +52,7 @@ export const debugFlags: Record<string, DebugFlag<boolean>> = {
 	forceSrgb: createDebugValue('forceSrgbColors', { defaults: { all: false } }),
 	debugGeometry: createDebugValue('debugGeometry', { defaults: { all: false } }),
 	hideShapes: createDebugValue('hideShapes', { defaults: { all: false } }),
+	documentName: createDebugValue('documentName', { defaults: { all: false } }),
 }
 
 declare global {