Clean up pre v4 release

[Helveg]

Describe the work done

Removed some dead pieces of code, and all connectivity and placement algorithms that haven't been adapted to v4 yet:

• TouchDetection
• FiberIntersection
• SatellitePlacement

Also removed ParticlePlacement in favor of RandomPlacement, because it was too slow and hand rolled to promote its use.

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📚 Documentation preview 📚: https://bsb--830.org.readthedocs.build/en/830/

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 74.48980% with 50 lines in your changes are missing coverage. Please review.

Project coverage is 86.73%. Comparing base (adc51d5) to head (23759db).

Files	Patch %	Lines
bsb/placement/random.py	77.21%	36 Missing :warning:
bsb/config/parsers.py	60.00%	8 Missing :warning:
bsb/config/__init__.py	44.44%	5 Missing :warning:
bsb/__init__.py	80.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #830 +/- ## ========================================== + Coverage 84.84% 86.73% +1.89% ========================================== Files 104 100 -4 Lines 13982 13345 -637 ========================================== - Hits 11863 11575 -288 + Misses 2119 1770 -349 ```

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