feat: add landing message to search page
This MR is a replicate of !45 (closed) considering recent changes to the search page and result list.
Steps:
- Go to search.html
- You should see a placeholder message below the search input
- It disappears when a valid search is made
- It appears back when the search query is empty and you hit the search button (This is new, do you like this style? We are preventing a search request at all here because I noticed that an empty string search produces a too verbose error here, maybe this is not fixed yet on BE.)
- No result msg works as before
closes #63 (closed)