feat: Add more information to errors if we think cookies are missing

[AshCorr]

What does this change?

If a user has cookies disabled the most likely error they'll encounter is a CSRF error as we expect this cookie to exist on almost every page visit and we check it before almost everything else.

I spent some time trying to add safety checks to everywhere we check for cookies, but that became a mess of trying to propagate the correct errors to the correct places and figuring out where we expect cookies to sometimes not exist. I think this approach should catch the vast majority, if not all, of users that don't have cookies enabled.

How to test

Turn off cookies and attempt a login, you should be redirected to a CSRF error page with the updated error message.

[github-actions]

Deploy build 10236 of identity:identity-gateway to CODE

All deployment options

• Deploy build 10236 of identity:identity-gateway to CODE
• Deploy parts of build 10236 to CODE by previewing it first
• What's on CODE right now?

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From guardian/actions-riff-raff.