Ability to set Policy/Initiative Assignments to DoNotEnforce

[h2floh]

Is your feature request related to a problem? Please describe.
We want to do a kind of assessment/reporting at a customer on how close or far they are away from being compliant with MCfS. For this we want to deploy/assign all compliance controls in an existing brownfield environment (see #14). In order to just get the compliance report and not prevent or interfere with daily business we want to set all assginments to 'DoNotEnforce' mode.

Describe the solution you'd like
A top level parameter which controls the EnforcementMode of all policy/initiative assignments.

Describe alternatives you've considered
Changing the existing bicep files.

Additional context
See PR #16 for further discussion.