frontend: Search

General goal of search directive:

1. When user types a string in the search bar, a drop-down menu autocompletes the string by providing a list of all categories and tags containing the user's string
2. If user clicks on one of the options provided by the autocomplete drop-down list, a request is sent to the database for all resources with foreign keys matching queried chosen tag or category
3. If user searchers for a string that's not in the set of categories or tags, no resources are loaded.