Level 1 measurement support in Sampler options

[gadial]

Summary

This PR adds support for level 1 measurement options in SamplerV2

Details and comments

This PR extends ExecutionOptionsV2 to a new class, SamplerExecutionOptionsV2 having an additional field meas_type which can accept the values "classified", "kerneled", "avg_kerneled", where "classified" represents the usual measurement level 2 output, and the other options represent measurement level 1 output.

Fixes part of #1554

[ihincks]

Thanks @gadial , one minore comment.

More generally, is the testing here in line with the standards of this library? I have an IQBackendWrapper < Backend class implement elsewhere if we want to use it.

[gadial]

More generally, is the testing here in line with the standards of this library? I have an IQBackendWrapper < Backend class implement elsewhere if we want to use it.

I added relevant tests for this PR to the existing ones; there are no extensive tests as far as I can see. However, Such a wrapper sounds like a good idea and I can add more exhaustive tests around it.

[coveralls]

Pull Request Test Coverage Report for Build 8650143258

Details

• 11 of 11 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 83.615%

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Totals
Change from base Build 8620306713:	0.02%
Covered Lines:	6236
Relevant Lines:	7458

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💛 - Coveralls