[TASK] Enabling the access to sensitivities from basicStatistics to validation algorithms in postprocesseor (i.e., representativity)

[Jimmy-INL]

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For some validation methods, derivative-based sensitivities are required. To initialize basic statistics at that level of the postprocessorInterface, few changes should take place in the validation gate.

Is your feature request related to a problem? Please describe.
representativity validation algorithm/postprocessor can not be implemented until the derivatives are available.

Describe the solution you'd like
Maybe instantiate the basic statistics from the rep postprocessor.

Describe alternatives you've considered
I do not have alternative suggestions but I am open to any ideas.

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For Change Control Board: Issue Review

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• 1. Is it tagged with a type: defect or task?
• 2. Is it tagged with a priority: critical, normal or minor?
• 3. If it will impact requirements or requirements tests, is it tagged with requirements?
• 4. If it is a defect, can it cause wrong results for users? If so an email needs to be sent to the users.
• 5. Is a rationale provided? (Such as explaining why the improvement is needed or why current code is wrong.)

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For Change Control Board: Issue Closure

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• 1. If the issue is a defect, is the defect fixed?
• 2. If the issue is a defect, is the defect tested for in the regression test system? (If not explain why not.)
• 3. If the issue can impact users, has an email to the users group been written (the email should specify if the defect impacts stable or master)?
• 4. If the issue is a defect, does it impact the latest release branch? If yes, is there any issue tagged with release (create if needed)?
• 5. If the issue is being closed without a pull request, has an explanation of why it is being closed been provided?