Fix for non-assignment of MAM policies

[markheydon]

App Protection policies use difference Graph resource for assignment, this passes that into the assign script to use when needed.

[markheydon]

Only tested locally and via manual assignment at this point, waiting for Standards to run to see what happens then on a production instance.

[markheydon]

@JohnDuprey fix worked on several overnight Standards runs, in that no errors now and policies are getting assigned to the custom groups. But exclusions aren't working by the looks (if they ever did?). Will look shortly at the exclusions issue.

[markheydon]

@JohnDuprey fixed issue of excluded groups not being process from Standards run. As per chat earlier though, obviously keep in mind this is the first time I've submitted a PR and can't say for 100% certainty I've caught all possible places the -ExcludeGroup stuff was missing. Certainly, working ok on Standards run locally for me now, and currently no support in the UI for manually deployed policies re an excluded group.