Fix parsing of huge OpenQASM 2 conditionals (backport #12774)

[mergify]

Summary

We fixed handling of giant integers in gate expression positions gh-12140, and this commit fixes the handling in conditionals. Unfortunately, this means pulling in big-int handling properly; the integers simply are bigints, and we're not immediately converting them into something else.

The need to support this may influence how the Rust-space data models of QuantumCircuit evolve.

Details and comments

Fix #12773

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This is an automatic backport of pull request #12774 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 85f9860 has failed:

On branch mergify/bp/stable/1.1/pr-12774
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  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   Cargo.lock
	modified:   crates/qasm2/Cargo.toml
	modified:   crates/qasm2/src/bytecode.rs
	modified:   crates/qasm2/src/lex.rs
	modified:   crates/qasm2/src/parse.rs
	new file:   releasenotes/notes/qasm2-big-condition-cfd203d53540d4ca.yaml
	modified:   test/python/qasm2/test_structure.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   Cargo.toml
	both modified:   crates/accelerate/Cargo.toml

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[coveralls]

Pull Request Test Coverage Report for Build 10166422540

Details

• 12 of 13 (92.31%) changed or added relevant lines in 2 files are covered.
• 4 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 89.967%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
crates/qasm2/src/lex.rs	5	6	83.33%

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	4	92.73%

Totals
Change from base Build 10152041064:	0.02%
Covered Lines:	61875
Relevant Lines:	68775

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💛 - Coveralls