Review architecture (onTimeModel vs modelHolder, etc.)

[ben-jy]

According to potential models that will be benchmarked, and the way we will benchmark them, architecture should be reviewed. We must define if it makes sense to create a new interface for benchmarked models, or if we use interface/class already defined in ontime (AbstractModel/Model, see https://github.com/ontime-re/ontime/tree/develop/src/ontime/core/modelling

[ben-jy]

For now, we created an interface AbstractBenchmarkModel (see https://github.com/ontime-re/ontime/tree/48-benchmarking-fix-zero-few-shot/src/ontime/module/benchmarking) that must implement every benchmark models. This class is completely independent from existing ontime model. We must therefore define if we keep the code this way or if we reuse existing class.