fix(ckeditor): makes sure basepath is set early enough

If CKEDITOR_BASEPATH is not set early enough, the editor will try to
load its theme files via the cache handler, which will fail.
fix(ckeditor): create a new input element was re-enabling other input fields

Added data-cke-init flag to distinguish between manually disabled ckeditors
and not yet initialized ones.
Merge pull request #6568 from sembrestels/ckeditor-init-fix2

Prevent CKeditor instances from being re-initialized