Make builtin qasm2.CustomClassical extensions Rust-native

[jeevan0920]

This PR is aimed at completing the PR at https://github.com/Qiskit/qiskit/pull/15560/changes

[qiskit-bot]

One or more of the following people are relevant to this code:

• @Qiskit/terra-core

[coveralls]

Coverage Report for CI Build 26281746248

Coverage increased (+0.02%) to 87.51%

Details

• Coverage increased (+0.02%) from the base build.
• Patch coverage: 11 uncovered changes across 2 files (209 of 220 lines covered, 95.0%).
• 10 coverage regressions across 2 files.

Uncovered Changes

File	Changed	Covered	%
crates/qasm2/src/bytecode.rs	122	112	91.8%
crates/qasm2/src/ext.rs	50	49	98.0%

Coverage Regressions

10 previously-covered lines in 2 files lost coverage.

File	Lines Losing Coverage	Coverage
crates/qasm2/src/parse.rs	6	97.62%
crates/qasm2/src/lex.rs	4	92.03%

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Coverage Stats

Relevant Lines:	123978
Covered Lines:	108493
Line Coverage:	87.51%
Coverage Strength:	957838.68 hits per line

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💛 - Coveralls

[Cryoris]

Hi Jeevan, could you document this PR a bit? What does this implement on top of #15560? And if this a draft, then we can mark it as such so we don't run the full CI on every commit.

[jeevan0920]

Hi Jeevan, could you document this PR a bit? What does this implement on top of #15560? And if this a draft, then we can mark it as such so we don't run the full CI on every commit.

Hi Julien, it is still work in progress, thanks for pointing out about the CI, I did not know about the draft PR thing.