Cookie issue fix

[Lanaparezanin]

Bug description:
Non-essential cookie __Controller::TempData appears eve though the user hasn't granted their consent.
Test by going to the following link: https://www.nuget.org/users/account/authenticate/return
The unknown error banner shouldn't appear:

Fix:
Added check to see if the user has granted consent.

Addresses https://github.com/orgs/NuGet/projects/21/views/1?filterQuery=assignee%3A%40me+milestone%3A%22Sprint+2026-01%22&pane=issue&itemId=147803039&issue=NuGet%7CEngineering%7C6244

[agr]

How __Controller::TempData cookie is non-essential? That's our only way of showing errors in some cases.

[Lanaparezanin]

How __Controller::TempData cookie is non-essential? That's our only way of showing errors in some cases.

@agr You could make a case for either, the argument for non-essential is that it is a convenience feature, doesn't break user's workflow, they just don't see the feedback messages. I didn't find any proper definition in ComplianceWeb's documentation about what exactly counts as essential. I can go to their office hours to sort this out, unless someone else has more context?

[joelverhagen]

I personally would argue that error/warning/info messages we put in TempData are essential. They describe status of work the user is doing. It's different from, say, Application Insights browser events sent by our JS.