Restructure the process of changing a password

+ Requests are now dispatched to the according user ressource, not the collection
+ The current user can be referenced by setting the pid to 'current'
+ Refactored the error logic

src/Controllers/common.ts

@@ -0,0 +1,20 @@
+export enum DataType {
+  STRING = "string",
+  NUMBER = "number",
+  INTEGER = "integer",
+  PERMISSION_LEVEL = "'ELEVATED' | 'STANDARD'",
+}
+
+interface Body {
+  [k: string]: DataType;
+}
+
+export function generateInvalidBodyError(body: Body) {
+  return {
+    type: "error",
+    payload: {
+      message: "The body of your request did not conform to the requirements",
+      schema: { body },
+    },
+  };
+}