Adds search by name functionality

* Adds methods to find by last name, convert to id, then return user objects
* Adjusts _show partial to only reflect name search or location search
This method looks identical to `location_search`. It feels like you don't really need to have a separate method to do these 2 parts.

For example, could `search_by_name` just be:

```ruby
def self.search_by_name(last_name_query)
  user_ids = User.where("last_name ILIKE ?", "#{last_name_query}").pluck(:id)
  User.where(id: user_ids)
end
```

It doesn't seem worth it right now to have 2 separate methods for each of these things.

Also consider renaming your argument. It's not really a query, its just a name or last_name