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

[mergify[bot]]

Summary

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

Details and comments

• as #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

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  This is an automatic backport of pull request #12579 done by Mergify.

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[coveralls]

Pull Request Test Coverage Report for Build 9676490291

Details

• 9 of 10 (90.0%) changed or added relevant lines in 2 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.02%) to 87.215%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/synthesis/discrete_basis/solovay_kitaev.py	8	9	88.89%
<!--	Total:	9	10	90.0%	-->

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	94.02%
crates/qasm2/src/lex.rs	3	93.13%
<!--	Total:	4		-->

Totals
Change from base Build 9665663824:	0.02%
Covered Lines:	74528
Relevant Lines:	85453

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💛 - Coveralls