Ref: Add concepts and restructure io directories

[niermann999]

Restructure the io folder to make it easier to understand which classes are part of the backend and which belong to the frontend:

• merge the json reader and writer to the json_converter. This way only the backend types are called "reader" and "writer"
• rename the "common" folder to "backend"
• move the detector related concepts to detray/core

Also factors out a function read_components_from_file from the detector reader, so that readers can be added to a detector construction workflow without calling the read_detector function (e.g. if some components should be read from file, while others are built/converted directly).

I tried to fix a nullptr dereferencing warning in the surface_factory_interface that appeared with gcc 14, but it seems to be a false positive

[sonarqubecloud]

Quality Gate passed

Issues
24 New issues
1 Accepted issue

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

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