Plug & play speaker diarization pipelines

[juanmc2005]

This PR addresses issue #96 and introduces a new feature for custom pipelines.

Changelog

• Add BasePipelineConfig and BasePipeline as minimal interfaces to respect for custom pipelines
  • A config must provide sample_rate, duration, step and latency
  • A pipeline must provide a config, it must be callable and be able to reset its internal state
• Make RealTimeInference, Benchmark and Optimizer fully compatible with any pipeline adhering to the interface
• Fix bug diart.tune doesn't initialize to custom hyper-parameters #96

The next step for custom pipelines would be that the CLI interface supports it, which is a bit more complicated because the CLI also builds the config.