[TASK] Move "skip_if_OS" to rook/tester.py

[wanghy-anl]

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Issue Description

Is your feature request related to a problem? Please describe.
I am developing some test cases for a workflow writer (test type is "RavenPython"), and I would like to skip the test if the OS is not Windows.

Describe the solution you'd like
Currently the "skip_if_OS" is only in RavenFramework. Joshua Cogliati mentioned it could probably be moved to rook/Tester.py so that it could be used by all the test types.

Describe alternatives you've considered
not yet

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For Change Control Board: Issue Review

This review should occur before any development is performed as a response to this issue.

• 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

This review should occur when the issue is imminently going to be closed.

• 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?