Support lazy build mode in the debugger

[annagrin]

Support debugging for a scenario when the app is broken into sub-apps that share the same memory as the main one but are built and loaded on demand while the app is running in the debugger.

• Update communication between injected client and dwds to allow sub-apps and their data to be updated on-the-fly

  • Migrate injected client to package:web for easier communication between dwds and injected client
    Migrate injected client to package:web #2338
    Migrate injected client to package web #2306
  • Add API to allow registering sub-apps in the injected client and dwds

• Support loading metadata for multiple apps in the debugger
  TODO: break into subtasks if needed