shell: Keep the search button on the right panel
I remember @aday complaining about the search button and the search bar being on different panels, and I agree it's problematic. I think the heart of the issue lies in the fact that the search button doesn't make sense in the left panel because the search isn't global but only for the Explore and Installed page, so it doesn't make much sense for it to be on the top-level panel. I think the UI is more consistent that way.
Before
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