Provide a trait for building inline form containers

Problem/Motivation

We provide a QuickFormElementsTrait that has a method called buildInlineContainer(), which is a helper for rendering form elements "inline" (next to each other) in quick forms.

This is provided by the farm_quick module, but would be useful outside of quick forms as well (eg: in other Drupal Form API forms in farmOS or contrib modules).

Proposed resolution

I propose we generalize this trait so that it can be used outside of quick forms, and deprecate QuickFormElementsTrait.

Remaining tasks

• Provide a trait for building inline form containers: FarmFormInlineContainerTrait
• Use FarmFormInlineContainerTrait instead of QuickFormElementsTrait in quick forms.
• Deprecate QuickFormElementsTrait.

User interface changes

None.

API changes

Provides a new FarmFormInlineContainerTrait that replaces the existing QuickFormElementsTrait.

Data model changes

None.