SG-786 - Fix 400 error code log outs without invalid_grant

[LRNcardozoWDF]

Type of change

• Bug fix
• New feature development
• Tech debt (refactoring, code cleanup, dependency upgrades, etc)
• Build/deploy pipeline (DevOps)
• Other

Objective

Be more precise to force log out when receiving 400 error code by ensuring that the response error is invalid grant.

Code changes

This is related to the clients PR 400s only log out on invalid grant error #3924

• ApiService.cs: After parsing the json, log out the user if the response error is "invalid_grant".

Screenshots

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[fedemkr]

I'd split this in two:
In the same place as it was before I'd leave:

if (authed
    &&
    (
        (logoutOnUnauthorized && response.StatusCode == HttpStatusCode.Unauthorized)
        ||
        response.StatusCode == HttpStatusCode.Forbidden
    ))
{
    await _logoutCallbackAsync(new Tuple<string, bool, bool>(null, false, true));
    return null;
}

and in on the new place:

if (authed && tokenError 
    &&
    response.StatusCode == HttpStatusCode.BadRequest 
    && 
    responseJObject?["error"]?.ToString() == "invalid_grant")
{
    await _logoutCallbackAsync(new Tuple<string, bool, bool>(null, false, true));
    return null;
}

The reason behind this is that if let's say that the status code is HttpStatusCode.Unauthorized then it will waste time reading the response content; so splitting it like this we gain performance on those cases.