Fix QASM2 if conditions

[david-pl]

Closes #707.

Changes:

• Add a deprecation warning to qasm2.extended.
• Properly handle more lenient syntax such as creg[0] == 1 when running PyQrack.
• Disallow anything but creg: Creg == x: int when trying to emit QASM2.
• Allow only x == y if both x and y are int | Bit | Creg anywhere using QASM2.

The issue with the more extensive syntax for emitting is that we don't have the runtime values. So you can't coerce e.g. creg[0] == 1 into a creg == x where x is an appropriate integer. This generally begs the question whether we want to support this kind of syntax since it is now support in some places, which might be confusing to users.

[github-actions]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
11254	9935	88%	0%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
src/bloqade/pyqrack/device.py	80%	🟢
src/bloqade/pyqrack/qasm2/core.py	85%	🟢
src/bloqade/qasm2/analysis/_init_.py	100%	🟢
src/bloqade/qasm2/analysis/validation/analysis.py	90%	🟢
src/bloqade/qasm2/dialects/indexing.py	85%	🟢
src/bloqade/qasm2/emit/target.py	81%	🟢
src/bloqade/qasm2/groups.py	98%	🟢
src/bloqade/qasm2/parse/lowering.py	76%	🟢
TOTAL	87%	🟢

updated for commit: c553a1c by action🐍

[codecov]

Codecov Report

❌ Patch coverage is 88.73239% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/bloqade/pyqrack/qasm2/core.py	80.00%	5 Missing ⚠️
src/bloqade/qasm2/analysis/validation/analysis.py	91.89%	3 Missing ⚠️

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[Roger-luo]

maybe to add some context - originalnly I supported the syntax creg[0] etc. because this is quite natural and convenient to use but this is not strictly the QASM2 specification, which is why this PR have to address the mismatch. As a side note, we are trying to support these convenient syntax for now but maybe we should just remove the support in the future if most usage goes to python kernel eventually.