Add field widget settings to read dynamic values from the fields.

Pushed a quick change regarding this.

To test,
* first goto manage-form of your content type.
* Change the dtuber field's widget settings
* set "Show additional fields in widget" -> checked
* create a new content
* upload the video
* input additional fields
* save
* verify the video got uploaded with the desired values.

This is an initial draft of the functionality, will refactor and push improved version of this in future. Needs review of this functionality.

Thanks!

This change is released to <2.0.4. Thus marking this as fixed.

Automatically closed - issue fixed for 2 weeks with no activity.