Copy-paste Theo's virtual_gate_sequence class into qualang-tools. #803

All 385 tests pass, 4 skipped in 45s

389 tests +389 385 ✔️ +385 45s ⏱️ +45s
    1 suites +    1     4 💤 +    4
    1 files +    1     0 ❌ ±    0

Results for commit 70c2c00. ± Comparison against earlier commit f552be2.