Start implementation of compat shim

[bwateratmsft]

Making as a draft PR to gather feedback.

[alexweininger]

We're currently storing branch data providers in a map using the Id passed during registration as the key. Currently, that Id wasn't used for anything, but now we are using that Id to lookup the BDP for a given application resource.

BranchDataProviderManager.ts where we find a branch data provider for a given application resource

Two things:

1. We should be mapping them by AzExtResourceType rather than type since type has some overlap
2. We'll have to update the Ids we're passing to registerAppResourceResolver in the client extensions, since they are random (some pass in the extensionId, others pass in resource type). We'll update them to use AzExtResourceType.

[bwateratmsft]

We're currently storing branch data providers in a map using the Id passed during registration as the key. Currently, that Id wasn't used for anything, but now we are using that Id to lookup the BDP for a given application resource.

BranchDataProviderManager.ts where we find a branch data provider for a given application resource

Two things:

1. We should be mapping them by AzExtResourceType rather than type since type has some overlap
2. We'll have to update the Ids we're passing to registerAppResourceResolver in the client extensions, since they are random (some pass in the extensionId, others pass in resource type). We'll update them to use AzExtResourceType.

I think once we've determined the BDP, we should attach it to RG's model objects for the entire tree. @philliphoff may already be doing that.

[alexweininger]

I believe all comments have been resolved.

[bwateratmsft]

I believe all comments have been resolved.