Merge current AutoQASM code from Braket SDK repo

[rmshaffer]

Issue #, if available: Move AutoQASM to new experimental repo

Description of changes: Merging the current version of the feature/autoqasm branch as of commit https://github.com/amazon-braket/amazon-braket-sdk-python/commit/d62e288961af1b9a42b14667e1167fca301e2708.

To review the actual code changes in this PR (vs. what is in the feature/autoqasm branch), see here: https://github.com/amazon-braket/autoqasm/compare/autoqasm-repo-1...autoqasm-repo-2

This package currently depends on the mcm-sim branch of both the amazon-braket-sdk-python and amazon-braket-default-simulator repos, in order to enable the version of the local simulator which supports mid-circuit measurement.

Note that the full commit history is preserved - this PR will be merged as a merge commit (not as a squash commit).

Tested the following things:

• [x] All tox stages succeed locally
• [x] codecov upload is working (currently does not provide reports because this repo is private)
• [x] Updated import cells in example notebooks, ensured notebooks still run
• [x] Set up sphinx build, generated documentation looks reasonable

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