qr lstsq implementation

[codecov[bot]]

Codecov Report

Patch coverage: 91.59% and project coverage change: -0.02% :warning:

Comparison is base (ddb041c) 91.89% compared to head (128b46e) 91.87%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #63 +/- ## ========================================== - Coverage 91.89% 91.87% -0.02% ========================================== Files 50 50 Lines 54627 54703 +76 ========================================== + Hits 50201 50261 +60 - Misses 4426 4442 +16 ``` | [Files Changed](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah) | Coverage Δ | | |---|---|---| | [faer-evd/src/hessenberg\_real\_evd.rs](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah#diff-ZmFlci1ldmQvc3JjL2hlc3NlbmJlcmdfcmVhbF9ldmQucnM=) | `93.79% <0.00%> (ø)` | | | [faer/src/lib.rs](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah#diff-ZmFlci9zcmMvbGliLnJz) | `81.08% <91.42%> (+0.12%)` | :arrow_up: | | [faer-core/src/householder.rs](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah#diff-ZmFlci1jb3JlL3NyYy9ob3VzZWhvbGRlci5ycw==) | `89.97% <100.00%> (+0.01%)` | :arrow_up: | | [faer-qr/src/col\_pivoting/solve.rs](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah#diff-ZmFlci1xci9zcmMvY29sX3Bpdm90aW5nL3NvbHZlLnJz) | `76.36% <100.00%> (+0.08%)` | :arrow_up: | | [faer-qr/src/no\_pivoting/solve.rs](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah#diff-ZmFlci1xci9zcmMvbm9fcGl2b3Rpbmcvc29sdmUucnM=) | `80.48% <100.00%> (+0.63%)` | :arrow_up: | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/sarah-ek/faer-rs/pull/63/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=sarah)

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