Load observation info with TableLoader; standardize id fields in containers

[LukasBeiske]

This adds an option to load the observation information from /configuration/observation/observation_block with TableLoader and join it to each event.

This also standardizes the obs_id, event_id and tel_id fields used in some containers to remove mismatching descriptions which led to some warnings when merging different tables.

[codecov]

Codecov Report

Base: 92.51% // Head: 92.52% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (39c06e4) compared to base (89add5c).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2096   +/-   ##
=======================================
  Coverage   92.51%   92.52%           
=======================================
  Files         199      200    +1     
  Lines       16561    16582   +21     
=======================================
+ Hits        15322    15343   +21     
  Misses       1239     1239           

Impacted Files	Coverage Δ
ctapipe/containers.py	100.00% <100.00%> (ø)
ctapipe/io/tableloader.py	98.41% <100.00%> (+0.06%)	⬆️
ctapipe/io/tests/test_table_loader.py	99.44% <100.00%> (+0.01%)	⬆️
ctapipe/io/simteleventsource.py	96.05% <0.00%> (-0.02%)	⬇️
ctapipe/coordinates/__init__.py	100.00% <0.00%> (ø)
ctapipe/reco/impact_distance.py
ctapipe/reco/tests/test_impact_distance.py
ctapipe/coordinates/utils.py	100.00% <0.00%> (ø)
ctapipe/coordinates/impact_distance.py	100.00% <0.00%> (ø)
ctapipe/coordinates/tests/test_impact_distance.py	100.00% <0.00%> (ø)

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