Refactor how section ordering is handled (#1837) ...

* Extract template customizations into own controller

* Refactor Template model methods

* Fix view logic in draggable sections

* Add button for customising phase

* Fix rubocop violations in GuidanceService

* Rename GuidanceService to GuidancePresenter

* Fix bug in phase preview order sections

* Refactor preview action/controller code

* Fix Section ordering in various views

* Fix rubocop violations

* Fix bug forcing Phases to be modifiable

* Fix broken tests

* Update method to check if section is draggable

* Extract copy action into its own resource

* Extract customization transfers to own controller

* Remove redundant routing condition

* Fix Rubocop violation issues

* Change condition for section draggable

* Refactor instance variable in PlansController

* Fix broken tests

* Add test support for 'de' locale

* Fix merge issue in plans controller

* Fix broken specs in plan#request_feedback

Remove redundant database tables and columns ...

Remove redundant columns and tables listed in #1382

Update models and factories with new schema structure comments.

Add schema structure to factories files

Fixed broken Plan specs after model

Add extra validations for all models ...

- Includes specs using the Shoulda gem
- Includes a refactoring of update_numbers to a "sortable" abstraction

Adding fixtures