Setup Firebase Firestore connecting to localhost

Firestore.swift

// Checking if unit tests are running
if ProcessInfo.processInfo.environment["unit_tests"] == "true" {
  print("Setting up Firebase emulator localhost:8080")
  let settings = Firestore.firestore().settings
  settings.host = "localhost:8080"
  settings.isPersistenceEnabled = false
  settings.isSSLEnabled = false
  Firestore.firestore().settings = settings
}