Array-api Linalg functions

It might be nice to add the following functions to blosc2, which are included in the linalg module of the array-api standard. See src/blosc2/linalg.py for function signatures.

- [ ] array_api_tests/test_linalg.py::test_cholesky
- [ ] array_api_tests/test_linalg.py::test_cross
- [ ] array_api_tests/test_linalg.py::test_det
- [ ] array_api_tests/test_linalg.py::test_diagonal
- [ ] array_api_tests/test_linalg.py::test_eigh
- [ ] array_api_tests/test_linalg.py::test_eigvalsh
- [ ] array_api_tests/test_linalg.py::test_inv
- [ ] array_api_tests/test_linalg.py::test_linalg_matmul - add @ operator
- [x] ~array_api_tests/test_linalg.py::test_matmul~
- [ ] array_api_tests/test_linalg.py::test_matrix_norm
- [ ] array_api_tests/test_linalg.py::test_matrix_power
- [ ] array_api_tests/test_linalg.py::test_matrix_rank
- [ ] array_api_tests/test_linalg.py::test_linalg_matrix_transpose
- [x] ~array_api_tests/test_linalg.py::test_matrix_transpose~
- [x] array_api_tests/test_linalg.py::test_outer (but this can be optimised since chunks don't need to be decompressed)
- [ ] array_api_tests/test_linalg.py::test_pinv
- [ ] array_api_tests/test_linalg.py::test_qr
- [ ] array_api_tests/test_linalg.py::test_slogdet
- [ ] array_api_tests/test_linalg.py::test_solve
- [ ] array_api_tests/test_linalg.py::test_svd
- [ ] array_api_tests/test_linalg.py::test_svdvals
- [ ] array_api_tests/test_linalg.py::test_linalg_tensordot
- [x] ~array_api_tests/test_linalg.py::test_tensordot~
- [ ] array_api_tests/test_linalg.py::test_trace
- [ ] array_api_tests/test_linalg.py::test_linalg_vecdot
- [x] ~array_api_tests/test_linalg.py::test_vecdot~
- [ ] array_api_tests/test_linalg.py::test_vecdot_conj
- [ ] array_api_tests/test_linalg.py::test_vector_norm

Start by reading the signatures in src/blosc2/linalg.py and the unchecked cases in array_api_tests/test_linalg.py. Run the relevant linalg tests to establish which functions are currently missing. Done means the listed unchecked tests pass and the checklist accurately reflects the remaining implementations.

Written by the indexing model from the issue text.