feat: fetch results in parallel

[PierrePicard20]

Motivation

Improve performance of results fetching.

Description

Execute callbacks in parallel.

Testing

Performance tests: ~30% improvement.
Non regression tests.

Impact

Callbacks are executed on different threads.

Additional Information

Added new application parameter ApplicationConfig.ParallelismLimit in appSettings.json: set the maximum number of threads that can run callbacks in parallel. When 0, the value set is the number of CPU cores. The default value is 0.

Checklist

• My code adheres to the coding and style guidelines of the project.
• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• I have thoroughly tested my modifications and added tests when necessary.
• Tests pass locally and in the CI.
• I have assessed the performance impact of my modifications.