fix: set disabled state properly

[arturovt]

Currently, it's not possible to provide the initial disabled value from the form control options, e.g.:

<editor [formControl]="control" [init]="{ ... }"></editor>

control = new FormControl({ value: '', disabled: true });

We already have the disabled property which will:

• call setMode if editor is already created
• set disabled property, thus it will be retrieved later within the finalInit object

[jscasca]

I think we are missing a setMode on an init_instance_callback to ensure the state is always the latest change.