Add `negativity` to `quantum_info.entanglement`

[renatomello]

This needs to be merged after #1454

EDIT: Also needs #1462

Checklist:

• [ ] Reviewers confirm new code works as expected.
• [x] Tests are passing.
• [x] Coverage does not decrease.
• [x] Documentation is updated.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.94%. Comparing base (c92f49c) to head (8ed5b54). Report is 12 commits behind head on partial_transpose.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## partial_transpose #1456 +/- ## ================================================== Coverage 99.94% 99.94% ================================================== Files 81 81 Lines 11740 11763 +23 ================================================== + Hits 11733 11756 +23 Misses 7 7 ``` | [Flag](https://app.codecov.io/gh/qiboteam/qibo/pull/1456/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/qiboteam/qibo/pull/1456/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | `99.94% <100.00%> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam#carryforward-flags-in-the-pull-request-comment) to find out more.

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[renatomello]

@AlejandroSopena @BrunoLiegiBastonLiegi @stavros11 this is ready but pointing to the partial_transpose branch in PR #1462. That PR needs to be merged before this one.