Add missing `hermitian` argument to `backend.calculate_eigenvalues` and `backend.calculate_eigenvectors` methods

[renatomello]

Closes #1447 together with https://github.com/qiboteam/qibojit/pull/188. Tests should be run locally to verify that they are passing on GPUs.

The numpy, numba, pytorch, and tensorflow backends already had this argument in their methods, but abstract, cupy, and cuquantum did not. This fixes the issue.

Checklist:

• [x] 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 (df709ce) to head (efb3f6a). Report is 9 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1448 +/- ## ======================================= Coverage 99.94% 99.94% ======================================= Files 81 81 Lines 11708 11708 ======================================= Hits 11701 11701 Misses 7 7 ``` | [Flag](https://app.codecov.io/gh/qiboteam/qibo/pull/1448/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/1448/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%> (ø)` | | 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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