[bootstrap-4] withTheme additional customization

[Pavinati]

Prerequisites

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

Description

The documentation describes the use of withTheme for the customization of the default theme.
Is there any plan to have something similar for bootstrap-4 too?
Say for example i want to use BS4 as default theme, but i want to change the standard <input> that comes with it.
Ideally i could use

import { withTheme } from '@rjsf/bootstrap-4';

MyForm = withTheme({ /* my customization object */ });

[jacqueswho]

There is a bootstrap-4 theme.

[Pavinati]

i was already using the bootstrap 4 theme, but it is missing features and I need some extra customization, that's why we I wanted to customize the already existing bootstrap 4 implementation
see #1962 #1963

[heath-freenome]

Fixed in the v5 beta, see the 5.x migration guide