When the `navigation_menu` site setting has been set to `sidebar` or
`header dropdown`, overriding the site setting via the `navigation_menu`
query params did not work.
Follow-up to c47015b861
What does this change do?
This commit the client to override the navigation menu setting
configured by the site temporarily based on the value of the
`navigation_menu` query param. The new query param replaces the old
`enable_sidebar` query param.
Why do we need this change?
The motivation here is to allow theme maintainers to quickly preview
what the site will look like with the various navigation menu site
setting.
