URLConfigs, Volume Plugins, S1 Plugin Split, Removal of electron_cloud data_kind

[HenningSE]

This PR will:

• replace all @strax.takes_config arguments by straxen.URLConfig
• add a centralized context definition so the default values can be set there

[HenningSE]

This PR grew a bit compared to the initial task. These things have been changed:

• Use straxen.URLConfig instead of strax.takes_config
• Define the simulation context and set all needed config values there. When fuse will be made public this part must be done somewhere else (cutax?)
• Prepare fuse for the integration of fastsim by splitting the S1 simulation plugin and changing the S2 simulation so they can be loaded along with microphysics_summary and the s1_photons.
• Remove epix detector module thing and replace it by VolumePlugins
• Add a VerticalMergerPlugin to simplify the combination of some Plugins.

[ramirezdiego]

After testing the notebook, I finally finished looking at all the code changes (there was a lot 😄), thanks for the patience.

To me this looks good and refines further the structure that we want, to deal with detector corrections and fast-sim implementation, also thanks to the extra couple of general plugins that you added. This is great work, @HenningSE :) !

Let's deal with the TOC and renaming issues in the next iterations, but merge all these changes now, so that we can already start working on top of the new structure.