[FEA]: STF logical token should be compatible with the freeze API

[caugonnet]

Is this a duplicate?

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Area

CUDA Experimental (cudax)

Is your feature request related to a problem? Please describe.

The freeze API in STF makes it possible to hold logical data without using tasks, so that user code can interoperate with STF resources outside tasks. Logical tokens are specific types of logical data which have no physical backing of the data, and are used purely for synchronization.

Describe the solution you'd like

Both mechanisms should be compatible, however the current API is based on a get() method to retrieve a copy of the logical data content. We should specify how this behaves with a token (eg. returning a dummy void_interface object), document it, and add some unit tests.

Describe alternatives you've considered

No response

Additional context

No response

[caugonnet]

This would be an essential feature to make #2674 a powerful mechanism

[caugonnet]

This is being implemented in #2674 along with unit tests