Restrict connectivity qubits

[Simone-Bordoni]

Provide option to the user to select which hardware qubits to use during routing.
#1085 task 2

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ea72695) 100.00% compared to head (38aa9bd) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1121   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           68        68           
  Lines         9790      9777   -13     
=========================================
- Hits          9790      9777   -13     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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[BrunoLiegiBastonLiegi]

Thanks @Simone-Bordoni, I have just some minor comments.