Link to qiskit.synthesis.unitary.aqc on API index page (backport #12331)

[mergify]

Before, qiskit.synthesis.unitary.aqc was autogenerated by autosummary rather than being manually created like we normally do in apidoc/. This had two issues:

1. The module does not show up in the API index page https://docs.quantum.ibm.com/api/qiskit, even though it shows up as top-level in the doc app's left table of contents
2. The header hierarchy is messed up due to an autosummary quirk that I could not figure out how to fix Fix unnecessary h1 header in module pages generated by autosummary documentation#1272

Using a dedicated page fixes both of these problems.

I named the file qiskit.synthesis.unitary.aqc to preserve the previous URL we had for the module, so that we don't need redirects. (Technically, Sphinx now puts the HTML file in the apidoc/ folder rather than stubs/, but the docs app doesn't care.)

All the other modules were fine.

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This is an automatic backport of pull request #12331 done by Mergify.

[qiskit-bot]

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• @Eric-Arellano
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[coveralls]

Pull Request Test Coverage Report for Build 8974113795

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 8 unchanged lines in 2 files lost coverage.
• Overall coverage remained the same at 89.63%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	2	93.38%
crates/qasm2/src/parse.rs	6	96.69%

Totals
Change from base Build 8941650954:	0.0%
Covered Lines:	62247
Relevant Lines:	69449

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💛 - Coveralls

[Eric-Arellano]

Thanks, @ShellyGarion. I don't have merge permissions if you could please queue this up to merge.

[ShellyGarion]

I'm sorry, but it seems that I can't merge to the stable branch either.