feat: configurable external fga server

[le-yams]

Add inputs so an external server can be used to perform the tests

Description

To be able to run the tests against a specific OpenFGA version, we have to use an external server instead of the cli built-in one.
The PR adds two optional inputs so the user can specify a server url and its token.
If the server url is not specified, the cli built-in server is used (current behavior)

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

[le-yams]

To be done: adding an example and a test in the workflow [edit] done [/edit]

[le-yams]

I added the job test_conditions_support in the test workflow which verifies that the action actually runs the tests against the specified server

[rhamzeh]

Thanks @le-yams! This is useful! Merging it. Hopefully some of the logic here can be dropped in a future iteration once we add the relevant flag in the CLI

Relevant conversation: openfga/cli#335

[yann-disanto]

Thanks @le-yams! This is useful! Merging it.

Thank you 😃

Hopefully some of the logic here can be dropped in a future iteration once we add the relevant flag in the CLI

Relevant conversation: openfga/cli#335

Awesome!