Add concise and detailed logs for shunt compensators activation

Please check if the PR fulfills these requirements

[ ] The commit message follows our guidelines
[ ] Tests for the changes have been added (for bug fixes / features)
[ ] Docs have been added / updated (for bug fixes / features)

Does this PR already have an issue describing the problem?

What kind of change does this PR introduce?

Feature

What is the current behavior?

No logs are generated for shunt compensators, when the delta between the discretized reactive value and the optimal reactive value given by the optimizer is too big, and thus can lead to further loadflow divergence problem.

What is the new behavior (if this is a feature change)? Concise and detailed logs are now generated for shunt compensators activation, when the delta between the discretized reactive value and the optimal reactive value is over a configured threshold.

Does this PR introduce a breaking change or deprecate an API?

[ ] Yes
[ ] No

If yes, please check if the following requirements are fulfilled

[ ] The Breaking Change or Deprecated label has been added
[ ] The migration steps are described in the following section

What changes might users need to make in their application due to this PR? (migration steps)

Other information:

powsybl / powsybl-optimizer

Add concise and detailed logs for shunt compensators activation #70

Quality Gate passed