Ktor API: Exposed Table Joins, API Key Authentication with X-API-KEY

Links: * GitHub Source Code: https://github.com/santansarah/ktor-city-api * Ktor API Key: https://github.com/LukasForst/ktor-api-key * Ktor Status Pages: https://ktor.io/docs/status-pages.html * Exposed Wiki: https://github.com/JetBrains/Exposed/wiki * City info: https://simplemaps.com/data/us-zips In Part 2, I'll go over: * Generating an API key * Exposed table joins * Ktor API Key Authentication * Ktor Dynamic Status Pages * GET API city data