Convert search queries to use APIv4

All search queries now use the charmstore APIv4 endpoints. Charm and bundle details now always query APIv3 when loading the details as a slight regression to allow us to move this forward incrementally. Because APIv4 no longer has bundle baskets I have attempted to build the old urls for the bundle details but unfortunately not all bundles have the necessary syntax so some will fail to load. This is an intermittent issue and will be fixed in the next follow-up
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