feat(hugr-py): Implement a custom TypeBound.__repr__().

[cqc-alec]

The way TypeBounds are represented in string representations such as

"FuncDefn(f_name='__neg__', inputs=[Tuple(Opaque(id='float64', bound=<TypeBound.Copyable: 'C'>, args=[], extension='arithmetic.float.types'),)], params=[], visibility='Private')"

is somewhat annoying. This PR implements a custom __repr__() that makes it eval()-able.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.36%. Comparing base (ff903be) to head (ff5ac86).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2727   +/-   ##
=======================================
  Coverage   83.36%   83.36%           
=======================================
  Files         267      267           
  Lines       52503    52505    +2     
  Branches    47214    47214           
=======================================
+ Hits        43770    43773    +3     
+ Misses       6355     6354    -1     
  Partials     2378     2378           

Flag	Coverage Δ
python	88.77% <100.00%> (+0.02%)	⬆️

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

☔ 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.