feat(ui-common): add content mock data for testing purposes

The content.ts file is added to the ui-common package's mocks directory. This file contains mock data for testing purposes, including a contentText variable, a lexicalEditorState variable, and a contentBySlugData object. These mock data can be used to simulate content-related data in unit tests or during development.

packages/ui-common/src/mocks/content.ts

@@ -0,0 +1,20 @@
+/* eslint-disable camelcase */
+const contentText = "Test Content"
+
+const lexicalEditorState = `{"root":{"children":[{"children":[{"detail":0,"format":0,"mode":"normal","style":"","text":"${contentText}","type":"text","version":1}],"direction":"ltr","format":"","indent":0,"type":"heading","version":1,"tag":"h1"},{"children":[{"children":[{"detail":0,"format":0,"mode":"normal","style":"","text":"International conferences dedicated to ","type":"text","version":1},{"detail":0,"format":2,"mode":"normal","style":"","text":"Dictyostelium","type":"text","version":1},{"detail":0,"format":0,"mode":"normal","style":"","text":" started in  1977 with the meeting in Sardinia, and continued on a roughly 3-year  cycle into the 1980's. However, as the field became more active, more  local meetings sprang up to fill the gaps in the cycle. Notable amongst  these was an annual series in the UK, which gradually became more  international. By the late 1980's with the successive meetings at  Amsterdam, Oxford, Airlie and Cambridge, the current pattern of annual  meetings was established. Interestingly in the late 1990's as the field  expanded further, local meetings were re-started in several countries.     ","type":"text","version":1}],"direction":"ltr","format":"","indent":0,"type":"paragraph","version":1}],"direction":"ltr","format":"","indent":0,"type":"flex-layout","version":1}],"direction":"ltr","format":"","indent":0,"type":"root","version":1}}`
+
+const contentBySlugData = {
+  id: "1a2b",
+  content: lexicalEditorState,
+  name: "Test Title",
+  slug: "testnamespace-test",
+  updated_at: "2020-01-01T17:50:12.427Z",
+  updated_by: {
+    id: "3c4d",
+    email: "rusty@holzer.com",
+    first_name: "Rusty",
+    last_name: "Holzer",
+  },
+}
+
+export { lexicalEditorState, contentBySlugData, contentText }