New/Remove-RubrikOrganization and tests

[shamsway]

Description

Added Add-RubrikOrganization and Remove-RubrikOrganization to add and remove organizations, and associated unit tests

Related Issue

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• If suggesting a new feature or change, please discuss it in an issue first.
• If fixing a bug, there should be an issue describing it with steps to reproduce

#338

Motivation and Context

Why is this change required? What problem does it solve?

Addresses #338

How Has This Been Tested?

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• Include details of your testing environment, and the tests you ran to see how your change affects other areas of the code, etc.

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Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

Go over all the following points, and put an x in all the boxes that apply. If you're unsure about any of these, don't hesitate to ask. We're here to help!

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTION document.
• I have updated the CHANGELOG file accordingly for the version that this merge modifies.
• I have added tests to cover my changes.
• All new and existing tests passed.

[chriswahl]

Tried both new cmdlets on Cluster B and Cluster C - worked fine.

[jaapbrasser]

Tested and approved, minor update to unit tests