Remove AppAuth and prepare for Rust OIDC. (#870)

ElementX/Sources/Other/Extensions/Dictionary.swift

@@ -24,4 +24,9 @@ extension Dictionary {
         }
         return String(data: data, encoding: .utf8)
     }
+    
+    /// Returns a dictionary containing the original values keyed by the results of mapping the given closure over its keys.
+    func mapKeys<T>(_ transform: (Key) -> T) -> [T: Value] {
+        .init(map { (transform($0.key), $0.value) }) { first, _ in first }
+    }
 }