The theme callback would set innerHTML on the header which wipes out the
dismiss button. With an inner div we can replace the inner HTML without
worrying about other elements in the header.
Closes#2799.
We used this to run vscodevim in the browser but it now has a version
that is able to run as a VS Code web extension. This does require an
update to our marketplace, however.
Add a short message above the search box on the Extensions panel. This
helps explain the extension divergence to the user.
If they click dismiss, it stores an item in localStorage to prevent the
message from showing up on subsequent loads.
Co-authored-by: Asher <ash@coder.com>
