🏷️ providing a convenient CircuitInputType

[burgholzer]

Description

This PR provides a convenient type that summarizes the default circuit inputs to the load method.
Special care is taken that this type is only defined in type checking environments and does not require importing optional dependencies that might not be available at runtime (such as qiskit).

Checklist:

• The pull request only contains commits that are related to it.
• I have added appropriate tests and documentation.
• I have made sure that all CI jobs on GitHub pass.
• The pull request introduces no new warnings and follows the project's style guidelines.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.7%. Comparing base (4363502) to head (6a4b2c5).
Report is 128 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
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  Coverage   91.7%   91.7%           
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  Files        148     148           
  Lines      14832   14832           
  Branches    2386    2386           
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  Hits       13603   13603           
  Misses      1229    1229           

Flag	Coverage Δ		*Carryforward flag
cpp	91.4% <ø> (ø)		Carriedforward from 4363502
python	99.7% <100.0%> (ø)

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
src/mqt/core/load.py	100.0% <100.0%> (ø)