[#5227] Make script to generate possible customers

[zuhdil]

TODO / Done

Summarize what has been changed / what has to be done in order to finalize the PR.

• Make script to generate list of organisation admins of possible RSR customers

Test plan

What tests are necessary to ensure this works or doesn't break anything working

• Manual test

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Related to #5227

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• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1204682486384223

[coveralls]

coverage: 68.049% (-0.3%) from 68.374% when pulling a913cc7 on 5227-non-paying-customers-still-have-access into 4da8949 on master.