Move closeAndGetPendingLocalState to IContainerExperimental

[anthony-murphy]

This change deprecates the experimental method closeAndGetPendingLocalState on IContainer and moves it to IContainerExperimental.
IContainerExperimental is an interface that is easily casted to, which enables partners to access experimental features for testing and evaluation.
Moving the experimental method off IContainer will reduce exposure and churn on that production interface as we iterate on and finalize our experimental features.
Experimental features should not be used in production environments.

[dannimad]

I would expect this change to affect blobIsAttached test at the very least cause it calls getPendingLocalState but I didn't dig much into it. Seems like everything passes.

[anthony-murphy]

I would expect this change to affect blobIsAttached test at the very least cause it calls getPendingLocalState but I didn't dig much into it. Seems like everything passes.

this is only the Container, not the ContainerRuntime