Add `.offcanvas-expand-*` functionality

Created by: leettaylor

Offcanvas can be wrapped in an .offcanvas-expand{-sm|-md|-lg|-xl|-xxl} class to determine when it's content collapses behind a button. In combination with other utilities, you can easily choose when to show or hide particular elements.

For Offcanvas that never collapse, wrap the Offcanvas with the .offcanvas-expand class. For Offcanvas that always collapse, don't wrap with any .offcanvas-expand class.

Usage

<div class="offcanvas-expand-md">
    <button class="btn btn-primary d-md-none" type="button" data-bs-toggle="offcanvas" data-bs-target="#offcanvasCollapse" aria-controls="offcanvasCollapse">
        Show Offcanvas
    </button>

    <div id="offcanvasCollapse" class="offcanvas offcanvas-end" aria-labelledby="offcanvasTitle">
        <div class="offcanvas-header">
            <h2 class="offcanvas-title" id="offcanvasTitle">Title</h2>
            <button type="button" class="btn-close" data-bs-dismiss="offcanvas" aria-label="Close"></button>
        </div>

        <div class="offcanvas-body">
            <ul>
                <li>One</li>
                <li>Two</li>
            </ul>
        </div>
    </div>
</div>

Almost identical to how it works with the Navbar that uses Offcanvas and expands to a normal navbar.