Update matrices.py

[bramathon]

Moved native gates to the top of the QUANTUM_GATES dictionary.

Description

When translating to quil from some other format, there might be multiple possible choices for a gate (eg "ISWAP" or "XY"). While in general, converters targeting native quil ought to limit themselves to native gates, moving the native gates to the top of the list will help push in the right direction.

Checklist

• The PR targets the rc branch (not master).
• Commit messages are prefixed with one of the prefixes outlined in the commit syntax checker (see pattern field).
• The above description motivates these changes.
• There is a unit test that covers these changes.
• All new and existing tests pass locally and on the PR's checks.
• Parameters and return values have type hints with PEP 484 syntax.
• Functions and classes have useful Sphinx-style docstrings.
• All code follows Black style and obeys flake8 conventions.
• (New Feature) The docs have been updated accordingly.
• (Bugfix) The associated issue is referenced above using auto-close keywords.
• The changelog is updated, including author and PR number (@username, Test ignore #1234).

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🎉 This PR is included in version 3.1.0-rc.5 🎉

The release is available on GitHub release

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[rigetti-githubbot]

🎉 This PR is included in version 3.2.0-rc.1 🎉

The release is available on GitHub release

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[rigetti-githubbot]

🎉 This PR is included in version 3.2.0 🎉

The release is available on GitHub release

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