Add cascade delete functionality to the cleaner

[Wambere]

We need to add functionality to allow cascade delete to the FHIR resources cleaner

This needs to be an optional flag -cd --cascade-delete which is false by default, and allows the user to automatically cascade delete linked/referenced resources

linked to:

• https://github.com/onaio/fhir-tooling/issues/101
• cascade-delete is implemented in the importer maybe a similar approach can be taken for this

[pld]

I thought the plan was to remove the cleaner entirely, and use the cleaning functionality in efsity?

[Wambere]

Leaving this comment link in response to the above just in case anyone is ever following up