Enforce function return types

Very useful for proto wire types as all fields are optional but not
always reflected in the generated type.

packages/status-communities/.eslintrc.json

@@ -14,7 +14,7 @@
   ],
   "globals": { "BigInt": true, "console": true, "WebAssembly": true },
   "rules": {
-    "@typescript-eslint/explicit-function-return-type": ["warn"],
+    "@typescript-eslint/explicit-function-return-type": ["error"],
     "@typescript-eslint/explicit-module-boundary-types": "off",
     "eslint-comments/disable-enable-pair": [
       "error",