Enable the arrow-body-style ESLint rule

This manually ignores some cases where the resulting auto-formatting would not, as far as I'm concerned, constitute a readability improvement or where we'd just end up with more overall indentation.

Please see https://eslint.org/docs/latest/rules/arrow-body-style

test/unit/scripting_spec.js

@@ -152,14 +152,12 @@ describe("Scripting", function () {
     });
 
     it("should get field using a path", async () => {
-      const base = value => {
-        return {
-          id: getId(),
-          value,
-          actions: {},
-          type: "text",
-        };
-      };
+      const base = value => ({
+        id: getId(),
+        value,
+        actions: {},
+        type: "text",
+      });
       const data = {
         objects: {
           A: [base(1)],