Use reactivity-API for all APIs

[mbeckem]

Use the reactivity-API for all APIs.

This issue seeks to replace all usages of custom state synchronization (raw events etc.) with a unified approach using the reactivity API.
Shared, reactive data should be placed into signals where it can be watched (or derived) efficiently.

• Packages
  • authentication (and authentication-keycloak): for authentication state
  • editing (workflow state)
  • map (MapModel and associated sub-objects (e.g. layers))
    • new APIs should be introduced to get the center, scale, extent, etc. using the reactivity API (based on the ol map)
    • hooks used across the project (e.g. useSublayers, useCenter, useScale, ...) can be simplified using useReactiveSnapshot
  • selection (status of SelectionSource)
• Decide if we should keep supporting the old events for backwards compatibility

[mbeckem]

PR: #347