feature: Add support for SerializableProgram abstraction to Device interface

[rmshaffer]

Issue #, if available:

Description of changes:
The scenario is that an external library like AutoQASM wants to create program objects which can be executed on Braket devices, including local simulators and AWS devices, but also wants the freedom to return (simulated) results in a format that does not necessarily match the Braket schema for gate model task results.

This change adds a minimal abstraction, SerializableProgram, which represents a program that can be serialized to OpenQASM. It adds support for this in the Device class so that these programs can be run on Braket, while also supporting a local simulator which wants to return a GateModelQuantumTaskResult directly rather than being forced to match the schema of GateModelTaskResult.

For example implementations of this abstraction, see:

• https://github.com/amazon-braket/autoqasm/blob/7e4441dd6cc42c1ee01b52d86e1ee7a04fa15b40/src/autoqasm/program/program.py#L121-L154
• https://github.com/amazon-braket/autoqasm/blob/7e4441dd6cc42c1ee01b52d86e1ee7a04fa15b40/src/autoqasm/program/program.py#L227-L261

Testing done:
Tests added to verify new code and maintain 100% code coverage.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (ec5edaf) to head (677d810).

Additional details and impacted files

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  Lines         8903      8917   +14     
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[yitchen-tim]

It adds support for this in the Device class so that these programs can be run on Braket, while also supporting a local simulator which wants to return a GateModelQuantumTaskResult directly rather than being forced to match the schema of GateModelTaskResult.

If the vision is to support any simulator that can execute OpenQASM, do you think it's worth creating a new result class instead of GateModelQuantumTaskResult? Currently, the MCM simulator writes results in the measurements field of GateModelQuantumTaskResult. Although GateModelQuantumTaskResult does not validate the field type, it does have type hint and doc that does not agree with the value written into the measurements field.

[rmshaffer]

If the vision is to support any simulator that can execute OpenQASM, do you think it's worth creating a new result class instead of GateModelQuantumTaskResult? Currently, the MCM simulator writes results in the measurements field of GateModelQuantumTaskResult. Although GateModelQuantumTaskResult does not validate the field type, it does have type hint and doc that does not agree with the value written into the measurements field.

You're right, using the measurements field for arbitrary output values is not really intended. To support arbitrary OpenQASM programs with output variables, eventually we would need a task result object which is more generic than the current GateModelTaskResult and GateModelQuantumTaskResult, both of which assume that the result of a task is a single bitstring. However, doing this correctly would involve defining a new task result schema (in the schemas repo) which I believe is beyond the scope of this PR.

One possible option for now would be to define some kind of generic QuantumTaskResult object which does not have any particular schema. But this feels like it would be a temporary solution and I'd be hesitant to add that now. Curious to get other thoughts on this.