Deprecate and remove SecurityAnalysisPreprocessor

[sylvlecl]

• Do you want to request a feature or report a bug?

Removal of obsolete / not easy to maintain component.

• What is the current behavior?

The plugin interface SecurityAnalysisPreprocessor may be used by third parties to customize the loading of security analysis inputs by the itools security-analysis command.

Its design is quite complicated, and it's likely that no one uses it outside of our RTE project that proposed it. Plus, it's not that powerful, because for instance it does not allow to add new input files to the command.

In the end:

• client projects that want to have a customized security analysis tool would be better off implementing their own one.
• removing this plugin mechanism will remove some maintenance burden from powsybl-core

We should first deprecate the plugin, then remove it in a further release.