Refactor naming of component schemas

[Pietfried]

OCPP Version

OCPP2.0.1

Describe the problem

After the coupling of component_schema files and config values introduced in #740 there are still some variable definitions, function names and arguments that use the term component_schema or schema like:
https://github.com/EVerest/libocpp/blob/main/lib/ocpp/v201/init_device_model_db.cpp#L114
or
https://github.com/EVerest/libocpp/blob/main/lib/ocpp/v201/init_device_model_db.cpp#L942

Describe your solution

The goal of this issue is to adjust the names of the variables, arguments and functions.

Additional context

No response