Python 3.12 and LST Prod6 MCs multi-telescope support

[IevgenVovk]

Various fixes to ensure compatibility with newer Python versions and LST Prod6 MCs (including multiple telescopes)

Changes

New:

• mc: prod6 dl1 files support
• data run: simulate arrival time per gamma-ray event, coherent across telescopes

Fixes:

• mc: fix pandas column value retrieval
• spectrum: add missing params conversion to units
• data run: add missing mc_src_name
• simrun: write events under the key from MC files instead of the hard-coded one

Refactoring:

• mc: refactor mccollection and mcsample to use a single base class to unify common methods

[IevgenVovk]

@mstrzys , I've relaxed the dependencies as we've agreed. On my laptop the code runs OK; I think we can merge this if you agree.