Add `CheckboxWithLabel` component (#7881)

This PR builds on top of #7878 by adding a general-purpose
`CheckboxWithLabel` component to use for checkboxes that have attached
labels.

This component encompasses the functionality of allowing to click on the
label to toggle the value of the checkbox.

There was only one other occurrence of a checkbox with a label—the
"Public" checkbox in the channel management modal—and this has been
updated to use `CheckboxWithLabel`.

Resolves #7794.

Release Notes:

- Added support for clicking the label of the "Public" checkbox in the
channel management modal to toggle the value
([#7794](https://github.com/zed-industries/zed/issues/7794)).