Branch selection

[thierry-martinez]

This commit adds an abstract class BranchSelector and the following branch selection strategies:

• RandomBranchSelector, which corresponds to the strategy that was already implemented.

• FixedBranchSelector, for a selector where a dictionary sets the outcome for each measurement.

• ConstBranchSelector, for a selector that always returns the same outcome, whatever the measurement is.

[codecov]

Codecov Report

❌ Patch coverage is 87.39496% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.28%. Comparing base (ff63f49) to head (2dab444).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
graphix/simulator.py	65.00%	14 Missing ⚠️
graphix/sim/tensornet.py	91.66%	1 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## master #300 +/- ##
==========================================
- Coverage 79.36% 79.28% -0.08% 
==========================================
Files 39 40 +1 Lines 5733 5794 +61 ==========================================
+ Hits 4550 4594 +44 - Misses 1183 1200 +17 

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[EarlMilktea]

@thierry-martinez I'm not against the concept of this PR but I cannot sure whether it is appropriate to introduce this feature to the untyped/obsolete simulators.

[thierry-martinez]

Granted. I just opened #312, which will hopefully help unblock this.

[thierry-martinez]

Branch selection is now ready for review with the typed simulator!

[thierry-martinez]

Thanks, @EarlMilktea, for your review!

@shinich1, I updated the documentation. Could you take a look at this PR and let us know what you think? Thanks!

[shinich1]

Sorry for the delay, looks great.