fix: revert assertions tuple key order change

[jpadilla]

Description

In v1.3.8, we introduced a change where that reordered fields on a tuple from object, relation, user to user, relation, object. Since assertions are currently stored as a marshaled binary in both Postgres and Mysql storage adapters, this meant that any assertion written before v1.3.8 would result in being read in an incorrect order.

For example, a request to write assertions:

{
  "assertions": [
    {
      "tuple_key": {
        "user": "user:annez",
        "relation": "owner",
        "object": "folder:2021-budget"
      },
      "expectation": true
    }
  ]
}

would be read back as

{
  "authorization_model_id": "01HH30F9Q8QWK3942DH4ZB2WNF",
  "assertions": [
    {
      "tuple_key": {
      "object": "user:annez",
      "relation": "owner",
      "user": "folder:2021-budget"
    },
    "expectation": true
    }
  ]
}

Important: any assertion written after running v1.3.8 will present the same problem after the changes in this pull request are merged.

References

openfga/api#123

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2b0ec48) 82.23% compared to head (cb4b9dd) 82.20%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1217      +/-   ##
==========================================
- Coverage   82.23%   82.20%   -0.02%     
==========================================
  Files          83       83              
  Lines        9572     9584      +12     
==========================================
+ Hits         7871     7878       +7     
- Misses       1346     1350       +4     
- Partials      355      356       +1     

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