GN-4529: ensure editor is only initialized after prefix attribute of wrapping div has been set

[elpoelma]

Overview

This PR ensures that the editor component is only initialized after the prefix attribute of it's wrapping container has been set.

This PR:

• introduces a setUpPrefixAttr modifier on the wrapping container which sets the prefix attribute. It also controls the ready property which indicates when the editor may be initialized.

• After the prefix attribute has been set, the ready property is set to true
• When the element linked to the setUpPrefixAttr modifier is destroyed, the ready property is set to false (as the prefix attribute no longer exists)
  => this also means that the setUpPrefixAttr modifier is not generic and is only meant to be used in combination with the wrapping container.

This PR should solve the issue with the datastore calculation after having saved a document. (When the datastore is calculated, the prefix attribute should be set)

connected issues and PRs:

Should solve GN-4529

How to test/reproduce

• Create an empty agendapoint
• Notice that you have the option to insert a template
• Save the document
• The options to insert templates should still be there.

Challenges/uncertainties

• The modifier to set the prefix attribute is necessary as ember does not allow to set the prefix attribute directly in a template (see [Bug] can not dynamically assign prefix attribute in templates emberjs/ember.js#19369)
• The new setUpPrefixAttr is not generic and should only be used once (as it controls the component property ready). I could not find a better way to solve this.

Checks PR readiness

• UI: works on smaller screen sizes
• UI: feedback for any loading/error states
• Check cancel/go-back flows
• Check database state correct when deleting/updating (especially regarding relationships)
• changelog
• npm lint

[piemonkey]

Huh, I don't get why this wasn't working with did-insert as I thought EditorContainer should only be initialised once this.ready is set to true?

Anyway, looks good.

[elpoelma]

Huh, I don't get why this wasn't working with did-insert as I thought EditorContainer should only be initialised once this.ready is set to true?

Anyway, looks good.

Yes, but the this.ready attribute was never reset to false when saving.