Expose Watchdog and Context on Editor class and update integrations.

[Reinmar]

Notes:

• We exposed Watchdog on the editor class in order to remove that specific dependency on the package. See Expose Context, EditorWatchdog, and ContextWatchdog as static editor properties. #13707.
• The Angular integration still has cke5-watchdog in its dependencies and imports it directly.
• Most likely, the same changes would make now sense in the React integration too.
• There's also Cannot find module 'ckeditor5/src/core' or its corresponding type declarations. ckeditor5-angular#364, but to my knowledge seems unrelated.

[niegowski]

In the react integration it was skipped because the code there is using inference for the editor type <TEditor extends Editor> and since the Editor class does not have those static fields (Context, EditorWatchdog, ContextWatchdog) we can't access them. Those fields are only on the EditorClassic level.

We decided we don't want the core package to depend on the watchdog package. I think we should revisit this decision.

[Reinmar]

How was that supposed to work in Angular integration then? Or it was something that we completely missed?

[niegowski]

Or it was something that we completely missed?

I think this is the case.

[Witoso]

Scope:

• Add ckeditor5-watchdog to the “Framework” layer and make the base Editor expose these
  • Simpler option.
  • Risk: circular dependency on types between the editor and watchdog interfaces.
• Update integrations.
  • This time let’s also update the integrations to verify that it all works together.

[Witoso]

Scope:

• Expose Context, EditorWatchdog, and ContextWatchdog as static editor properties of the base Editor class.
• Remove Context, EditorWatchdog, and ContextWatchdog from editor implementations (e.g., ClassicEditor).
  • keep the tests so we have an additional layer of checks.
• Update docs.