Add keydown listener to `backdrop` to enable static `offcanvas` to close on `Esc`

Description

Added keydown event listener to backdrop. Updated static offcanvas to close on esc when data-bs-keyboard = true, which is also the current default setting for this attribute. If data-bs-keyboard = false the offcanvas will not close on any esc press.

Motivation & Context

This is a bug fix and provides offcanvas with similar behavior on esc keydown to modal, esc pressed on either static offcanvas or its backdrop will close it.

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

Change can be verified using this code snippet (showcases all scenarios):

<!--Static offcanvs with data-bs-keyboard=true closes on esc-->
    <button class="btn btn-primary" type="button" data-bs-toggle="offcanvas" data-bs-target="#staticBackdrop"
        aria-controls="staticBackdrop">
        static offcanvas closes on esc
    </button>
    <div class="offcanvas offcanvas-start" data-bs-backdrop="static" data-bs-keyboard="true" tabindex="-1"
        id="staticBackdrop" aria-labelledby="staticBackdropLabel">
        <div class="offcanvas-header">
            <h5 class="offcanvas-title" id="staticBackdropLabel">Offcanvas</h5>
            <button type="button" class="btn-close" data-bs-dismiss="offcanvas" aria-label="Close"></button>
        </div>
        <div class="offcanvas-body">
            <div>
                I will not close if you click outside of me, but will close on esc
            </div>
        </div>
    </div>

    <!--Static offcanvs with data-bs-keyboard=false attribute dosen't close on esc-->
    <button class="btn btn-primary" type="button" data-bs-toggle="offcanvas" data-bs-keyboard="false"
        data-bs-target="#staticBackdropNoKeyboard" aria-controls="staticBackdrop">
        static offcanvas closes on esc
    </button>
    <div class="offcanvas offcanvas-start" data-bs-backdrop="static" tabindex="-1" id="staticBackdropNoKeyboard"
        aria-labelledby="staticBackdropLabel">
        <div class="offcanvas-header">
            <h5 class="offcanvas-title" id="staticBackdropLabel">Offcanvas</h5>
            <button type="button" class="btn-close" data-bs-dismiss="offcanvas" aria-label="Close"></button>
        </div>
        <div class="offcanvas-body">
            <div>I will not close if you click on press esc outside of me.</div>
        </div>
    </div>

    <!--Non-static offcanvs behavior not changed-->
    <button class="btn btn-primary" type="button" data-bs-toggle="offcanvas" data-bs-target="#nonStaticBackdrop"
        aria-controls="staticBackdrop">
        non-static offcanvas
    </button>
    <div class="offcanvas offcanvas-start" tabindex="-1" id="nonStaticBackdrop" aria-labelledby="staticBackdropLabel">
        <div class="offcanvas-header">
            <h5 class="offcanvas-title" id="staticBackdropLabel">Offcanvas</h5>
            <button type="button" class="btn-close" data-bs-dismiss="offcanvas" aria-label="Close"></button>
        </div>
        <div class="offcanvas-body">
            <div>I will close if you click outside of me.</div>
        </div>
    </div>

Related issues

Closes #37155