Basis rotation for measurement

[chmwzc]

The next version of Qibo (0.1.12) will allow for measurements in the Pauli X/Y basis. #799
When it's released, I'll probably combine that with the expectation_from_samples function.
Tentatively, we can move the expectation (from state vector) and eigenvalues class functions out from the Molecule class then too.

[yjmaxpayne]

0.1.12 has been released. Suggest keeping an eye o 0.1.13 milestones as well: https://github.com/qiboteam/qibo/milestone/6 while working on changes in 0.1.12.

[chmwzc]

Stuck because of expectation_from_samples issue
Possible to write a workaround, but troublesome
Hopefully can be resolved within Qibo itself

[chmwzc]

Just a minor note, looks like there'll be some progress on my issue in the main Qibo repo in Aug, will resolve this once that's done 👍