Save the timestamp of the last project authorisation recalculation

What does this MR do and why?

Save the timestamp of the last project authorisation recalculation. Primary use case of this field is to get better visibility on when the authorisation is updated for the given user. This helps in investigating and debugging inconsistency in authorisation rules. We don't have any plan for using this field for any user facing UI for now.

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Fixes #425401 (closed)