test(bruno): Add API tests for Kobo, Koreader, OPDS, collections

- Add Kobo bookmark/markup sync tests
- Add Koreader progress/bookmark sync tests
- Add OPDS feed tests
- Add collection tests
- Add sync tests for book linking

bruno/sync-kobo/get-unlinked-books.bru

@@ -0,0 +1,21 @@
+meta {
+  name: "Get Unlinked Books - User View"
+  type: http
+  seq: 4
+}
+
+get {
+  url: {{base_url}}/api/sync/unlinked-books
+  body: none
+  auth: {
+    type: bearer
+    bearer: {{user_token}}
+  }
+}
+
+assert {
+  response.status == 200
+  response.body.unlinked exists()
+  response.body.total exists()
+  response.body.total >= 0
+}