Bugfix dump methods

[Q-lds]

Description

Bug Fixes and Enhancements:

• q.dump was not working for some backends. The issue was the wrong serialization of numpy values (measurement results and costs, both in the intermediate and in the optimized result)
• Target and Cloud in the header are now automatically inferred
• Some standard QAOA values are automatically added to the header's metadata
• function naming
• variable names
• fix some issues related to flake8

Checklist

• I have performed a self-review of my code.
• I have commented my code and used numpy-style docstrings
• I have made corresponding updates to the documentation.
• My changes generate no new warnings
• [x I have added/updated tests to make sure bugfix/feature works.
• New and existing unit tests pass locally with my changes.

[codecov]

Codecov Report

Merging #225 (58a5d08) into dev (945ae3f) will decrease coverage by 0.24%.
The diff coverage is 96.53%.

@@            Coverage Diff             @@
##              dev     #225      +/-   ##
==========================================
- Coverage   97.72%   97.48%   -0.24%     
==========================================
  Files          37       37              
  Lines        6771     6932     +161     
==========================================
+ Hits         6617     6758     +141     
- Misses        154      174      +20     

Impacted Files	Coverage Δ
tests/test_backends.py	50.74% <ø> (-0.73%)	⬇️
tests/test_circuit_routing.py	71.70% <75.00%> (-0.28%)	⬇️
tests/test_qpu_qiskit.py	88.88% <76.00%> (-6.20%)	⬇️
tests/test_problems.py	99.15% <99.15%> (-0.01%)	⬇️
tests/test_benchmark.py	99.61% <100.00%> (+0.01%)	⬆️
tests/test_converters.py	100.00% <100.00%> (ø)
tests/test_notebooks.py	94.11% <100.00%> (+0.11%)	⬆️
tests/test_operators.py	100.00% <100.00%> (ø)
tests/test_qpu_braket.py	95.27% <100.00%> (ø)
tests/test_qpu_devices.py	98.63% <100.00%> (ø)
... and 2 more

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