Refine SONATA output handling

[ilkilic]

This PR improves SONATA output handling by:

• Fixing the default spikes_file name (to out.h5) if not specified
• Using spike_location from config when recording spikes
• Correcting dt logic in report writing:
  • Downsampling now applies if report_dt > sim_dt
  • If report_dt < sim_dt, it’s clamped to sim_dt with a warning

[codecov]

Codecov Report

Attention: Patch coverage is 84.21053% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
bluecellulab/simulation/report.py	78.57%	3 Missing ⚠️

Files with missing lines	Coverage Δ
...ellulab/circuit/config/sonata_simulation_config.py	96.87% <100.00%> (ø)
bluecellulab/circuit_simulation.py	85.83% <100.00%> (-0.05%)	⬇️
tests/test_circuit/test_iotools.py	90.90% <100.00%> (ø)
bluecellulab/simulation/report.py	82.97% <78.57%> (-0.75%)	⬇️

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[darshanmandge]

I tested the code to generate reports for a small microcircuit and results also work with bluepysnap. Thanks @ilkilic!
Just mentioning here that the report.py code will be refactored later to have a similar structure as Report class of neurodamus. More tests will be added later to increase the coverage, too :)