Change Identity from UInt8Array to Identity to match other SDKs

[dbrinkmanncw]

Description of Changes

Describe what has been changed, any new features or bug fixes

UInt8Array -> Identity
Reducer callbacks now get a ReducerEvent instead of just caller and status

API

• [X ] This is an API breaking change to the SDK

If the API is breaking, please state below what will break

Projects using this SDK will need to:

• update their references to identities from UInt8Arrays to Identity
• update any reducer callbacks to take a ReducerEvent as the first argument

Requires SpacetimeDB PRs

List any PRs here that are required for this SDK change to work

clockworklabs/SpacetimeDB#94

[mamcx]

The Identity in places like readme.md, client_api.ts (like export interface Event), App.tsx, spacetimedb_client.ts are not updated with the new class.

Is likely some take advantage of weak typing, but wonder if is the desirable outcome.

[drogus]

Looks great!