enh(ci): add some metrics on Sight CI
Description
These changes will add metrics on Sight CI, which will allow to easily see some essential piece of information on the state of the project and how an MR will change that.
Closes #489 (closed)
How to test it?
Check if the metrics are generated and are consistent with the reality.
Additional tests/tasks to run
For now, there is only the number of warnings and the number of deprecated declarations. We should think of and add some other metrics.