Menu toggle button sub-template

Problem/Motivation

In ✨ Break-up menu template into sub-templates Active we created a new template for the SVG icon of the toggle button. Unsure if we still want to create a sub-template / override for the button portion, but opening here to preserve that original intent. (We may decide to close later if this is not actually a useful thing to do for people).

Proposed resolution

Create a Twig template for the button/toggle

Remaining tasks

1. determine if we actually care to do this :)

2. make the button its own template