[TASK] Add methods to switch MSW steps programatically

The module `@typo3/backend/multi-step-wizard` now has two additional
methods to allow switching to the previous or next step programatically:

* `previous()`
* `next()`

The current jQuery hack in EXT:form's wizard is now using the introduced
`next()` version.

Resolves: #103280
Releases: main
Change-Id: I50e6e3f499ddbf50a912bc6f5b7d2c557c45e9b5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/83210


Tested-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Tested-by: Andreas Nedbal <andy@pixelde.su>
Reviewed-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: Andreas Kienast <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Reviewed-by: Andreas Nedbal <andy@pixelde.su>