[PLT-7793] Add /users/tokens/search endpoint (#8088)

* Add /users/tokens/search endpoint + tests

* Fix check-style

* Unnecessary deletion

i18n/en.json

@@ -6842,6 +6842,10 @@
     "id": "store.sql_user_access_token.get_by_user.app_error",
     "translation": "We couldn't get the personal access tokens by user"
   },
+  {
+    "id": "store.sql_user_access_token.search.app_error",
+    "translation": "We encountered an error searching user access tokens"
+  },
   {
     "id": "store.sql_user_access_token.save.app_error",
     "translation": "We couldn't save the personal access token"