[bootstrap-4] Widget and FieldTemplate customisation

[stufisher]

Prerequisites

• [ x ] I have read the documentation;
• [ x ] In the case of a bug report, I understand that providing a SSCCE example is tremendously useful to the maintainers.
• [ x ] Ideally, I'm providing a sample JSFiddle or a shared playground link demonstrating the issue.

Description

The boostrap-4 theme widgets now wrap each form control in a Form.Group directly with the label:
https://github.com/rjsf-team/react-jsonschema-form/blob/master/packages/bootstrap-4/src/TextWidget/TextWidget.tsx

this makes it pretty difficult to customise the form layout by providing a custom FieldTemplate. The only way to do this is to now copy and paste each widget you need and modify them independently.

Previously you could inject a customised FieldTemplate and thus override the label / field positioning as the label was part of the FieldTemplate and not the specific Widget in question

Steps to Reproduce

Expected behavior

It would be better for customisation if the label was injected from the FieldTemplate rather than in each widget (as this worked previously)

Actual behavior

You have to modify every Widget class rather than the FieldTemplate

Version

@rjsf/bootstrap-4: ^2.3.0
@rjsf/core: ^2.1.0

[newt10]

Addressed by PR #2533