Adding unrolling to spin echo

[andrea-pasquale]

Closes #724.
I've added the option to unroll sequences when running spin echo which should improve performances.
There was also a typo since the protocol spin_echo_sequences was actually implementing spin_echo_signal which I fixed.

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.
• Compatibility with Qibo modules (Please edit this section if the current pull request is not compatible with the following branches).
  • Qibo: master
  • Qibolab: main
  • Qibolab_platforms_qrc: main

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7c4d9d3) 97.15% compared to head (c671919) 97.20%.

Additional details and impacted files

@@              Coverage Diff              @@
##           spin_echo     #725      +/-   ##
=============================================
+ Coverage      97.15%   97.20%   +0.04%     
=============================================
  Files            110      110              
  Lines           7635     7659      +24     
=============================================
+ Hits            7418     7445      +27     
+ Misses           217      214       -3     

Flag	Coverage Δ
unittests	97.20% <100.00%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/qibocal/protocols/characterization/__init__.py	100.00% <100.00%> (ø)
.../protocols/characterization/coherence/spin_echo.py	100.00% <100.00%> (ø)
...ols/characterization/coherence/spin_echo_signal.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

[Jacfomg]

It runs in Zurich and the pulses are fine and everything, i did not run on calibrated qubit thought. The code also looks fine.