Fix field mask extraction in device create/update operations

[kschiffer]

Summary

The SDK automatically extracts the field masks of a device patch in Set operations. However, the extraction is in its current state simply extracting all possible leaf-paths of a patch without verifying whether they can be used as a valid field mask.
When e.g. trying to patch the locations property of a device, this leads to problems as the SDK tries to set field masks like locations.user.latitude, which is invalid because the location property can only be set as a whole.

Steps to Reproduce

1. Try to set e.g. the locations property of a device
2. Retrieve an error for using invalid field masks

What do you see now?

Not possible to set some properties of a device.

What do you want to see instead?

Correct field mask extraction and no errors.

Environment

SDK in node js or browser.

How do you propose to implement this?

The SDK needs to apply only the deepest possible field mask by checking back with the device entity map (sdk/js/generatesd/device-entity-map.json)

Additionally, this will necessitate an update to the device entity map which is set up quite roughly only at the moment.

Can you do this yourself and submit a Pull Request?

Yes.