Feature/661 Azure specific resource group

[Looyyd]

Description

Allows to add the flag --resource-group "RG_NAME" to only scan the specified resource group in Azure.

This is achieved by passing the value of the flag up the abstractions until the facade creation. Then when resources are fetched the Facade classes check if self.resource_group is set, and if it is, it only fetches from that resource group using the appropriate APIs (either list_by_resource_group(resource_group_name=self.resource_group) or list(resource_group_name=self.resource_group) ).
Not sure if this is the best place to put it, let me know if you want refactoring.

I tested it on resources that I spawned up and it worked, I didn't see any existing relevant test suites for Azure.

Didn't modify Facade for AAD, RBAC and security center since those checks are inherently subscription level checks.

Fixes #661

Type of change

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• 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 not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works (optional)
• New and existing unit tests pass locally with my changes