CKEditor

We migrated away from the legacy CKEditor builds using Webpack and instead use the prebuilt npm binaries.
The role of the packages/ckeditor5 is to gather the CKEditor for consumption by the client, which includes plugin definitions.
The internal Trilium plugins (e.g. cut to note, include note) are present in packages/ckeditor5/src/plugins.
External CKEditor plugins that needed adjustments are present in packages/ckeditor5-*.
- To integrate a new plugin, see Plugin migration guide.