FR: Support Codable in Document Update

### Feature proposal

* Firebase Component: Firestore

Currently Codable in Swift works for `setData(from: Codable)`, but there is no equivalent `updateData(from Codable)`.

This means that if you you want to update a document that is represented by a `Codable` type, there is no straightforward way to update the document. Using `setData` again is not a good option either, as other clients will see that as an `added` event and not a `modified` event.

Additionally, using Codable encodes `Date` as a `FIRTimestamp`, but manually converting a Codable object to `[AnyHashable: Any]` using `JSONSerialization` erases these types and instead encodes it as `Double`, breaking other feature such as using a listener with a date filter.