Added Offcanvas scroll after close option

[Xcreen]

Description

I added a option scrollAfterClose to be able to disable the scrolling to the offcanvas toggler after the offcanvas is closed.

Motivation & Context

Currently after the offcanvas is closed, the body always scrolling back to the offcanvas toggler position.
When enable offcanvas bodyscrolling and add anchor-links into the offcanvas, the links dont work.

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

• https://deploy-preview-40553--twbs-bootstrap.netlify.app/

Related issues

Closes #38070

[patrickhlauke]

noting that this isn't about scrolling. scrolling is a side effect of focus being (correctly) set back to the element that triggered the offcanvas. so, at the very least, rename this to be about focus, not scroll.