fix: #156 improve search speed + add keys to list elements

Summary of changes:

• Update whitespaces for consistent code layout 🙏
• Add key tags wherever react would like to have those 🏷
• Introduce a query_tokens field to initiatives' translations for speeding up search. It holds a initiative's title, short description and description with all-lowercase. ⛵
• Searches for tag-matches by slug instead of title and eliminates by this an expensive map generation. 🚤