derived presence state (#1204)

This PR adds

- A new `TLInstancePresence` record type, to collect info about the
presence state in a particular instance of the editor. This will
eventually be used to sync presence data instead of sending
instance-only state across the wire.
- **Record Scopes**

`RecordType` now has a `scope` property which can be one of three
things:
- `document`: the record belongs to the document and should be synced
and persisted freely. Currently: `TLDocument`, `TLPage`, `TLShape`, and
`TLAsset`
- `instance`: the record belongs to a single instance of the store and
should not be synced at all. It should not be persisted directly in most
cases, but rather compiled into a kind of 'instance configuration' to
store alongside the local document data so that when reopening the
associated document it can remember some of the previous instance state.
Currently: `TLInstance`, `TLInstancePageState`, `TLCamera`, `TLUser`,
`TLUserDocument`, `TLUserPresence`
- `presence`: the record belongs to a single instance of the store and
should not be persisted, but may be synced using the special presence
sync protocol. Currently just `TLInstancePresence`

This sets us up for the following changes, which are gonna be pretty
high-impact in terms of integrating tldraw into existing systems:

- Removing `instanceId` as a config option. Each instance gets a
randomly generated ID.
- We'd replace it with an `instanceConfig` option that has stuff like
selectedIds, camera positions, and so on. Then it's up to library users
to get and reinstate the instance config at persistence boundaries.
- Removing `userId` as config option, and removing the `TLUser` type
altogether.
- We might need to revisit when doing auth-enabled features like locking
shapes, but I suspect that will be separate.

packages/utils/api-report.md

@@ -37,6 +37,13 @@ export type ErrorResult<E> = {
 // @internal (undocumented)
 export function exhaustiveSwitchError(value: never, property?: string): never;
 
+// @internal
+export function filterEntries<Key extends string, Value>(object: {
+    [K in Key]: Value;
+}, predicate: (key: Key, value: Value) => boolean): {
+    [K in Key]: Value;
+};
+
 // @internal (undocumented)
 export function getErrorAnnotations(error: Error): ErrorAnnotations;