Use built-in IPython code highlighting in formatted OQ2 output

[jakelishman]

Summary

We currently have an option to QuantumCircuit.qasm that produces rich formatted output for IPython/Jupyter contexts. This involves a lot of manual handling, while modern IPython has the IPython.display.Code object for representing things. This commit switches over to preferentially using this, if the user has a Pygments lexer capable of handling the qasm2 alias available.

This is part of an effort to fully deprecate the qiskit.qasm package (in favour of qiskit.qasm2, where appropriate), and to trim down extra components where there are supported alternatives.

Details and comments

Depends on #9944.

[qiskit-bot]

Thank you for opening a new pull request.

Before your PR can be merged it will first need to pass continuous integration tests and be reviewed. Sometimes the review process can be slow, so please be patient.

While you're waiting, please feel free to review other open PRs. While only a subset of people are authorized to approve pull requests for merging, everyone is encouraged to review open pull requests. Doing reviews helps reduce the burden on the core team and helps make the project's code better for everyone.

One or more of the the following people are requested to review this:

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 5574953194

• 4 of 20 (20.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.009%) to 86.056%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/circuit/quantumcircuit.py	4	20	20.0%

Files with Coverage Reduction	New Missed Lines	%
qiskit/extensions/quantum_initializer/squ.py	2	80.0%
crates/qasm2/src/lex.rs	4	90.89%

Totals
Change from base Build 5559766630:	-0.009%
Covered Lines:	72271
Relevant Lines:	83981

---

💛 - Coveralls

[mtreinish]

Can we remove the on hold with this since #9944 has merged? (I assume it needs the rebase because it did merge)

[jakelishman]

Now rebased over main, but looking at the PR with fresh eyes, the path forwards may just be to close it and simply not include a formatted option once QuantumCircuit.qasm is moved to qiskit.qasm2.dumps.

[jakelishman]

I think I'm going to close this - we can probably just keep the current form kicking until we fully remove the formatted option by nature of not transferring it over to the new qiskit.qasm2.dumps introduced in #10533.