[search] Redesign search features
- rearrange layout (template & css) for sort filters on start page
- add global search and filter options on start page
- add search feature in navigation
- rearrange layout (template & css) on search results page
To be ported from Guides:
- https://gitlab.com/HistoryAtState/guides/commit/d14c9001ab8688e60015f2dd39e9140b01562e1b
- Most commits from https://gitlab.com/HistoryAtState/guides/merge_requests/18/commits
Related feature requests #76 , #67 (closed)