Fix some bugs in loading Solovay Kitaev decompositions (backport #12579)

[mergify]

Summary

Fixes #12576 and some other small bugs in storing & loading basic approximations for the Solovay Kitaev algorithm.

Details and comments

• as Solovay Kitaev Decomposition doesn't correctly load saved approximations from file #12576 mentioned, there is a missing .item() unwrapping when loading the dictionary from the npy file
• reloading the gate sequence also missed the correct labels and global_phase
• a test is now checking all of the above works correctly

---

This is an automatic backport of pull request #12579 done by [Mergify](https://mergify.com).

[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 following people are relevant to this code:

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 9676490156

Details

• 9 of 10 (90.0%) changed or added relevant lines in 2 files are covered.
• 9 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.04%) to 89.956%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/synthesis/discrete_basis/solovay_kitaev.py	8	9	88.89%

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	94.02%
crates/qasm2/src/lex.rs	2	92.62%
crates/qasm2/src/parse.rs	6	97.61%

Totals
Change from base Build 9663344566:	0.04%
Covered Lines:	61849
Relevant Lines:	68755

---

💛 - Coveralls