Clean up usage of processing configuration, knowledge base and session

[joachimmetz]

Clean up usage of processing configuration, knowledge base and session

• session to contain basic information about invocation of tools
• processing / session configuration to contain tool provided options
• knowledge base to contain values derived from the source data

Use the mediator to interface between processing / session configuration and knowledge base. For now have processing / session configuration override those derived from the source data

To consider:

• support more than 1 host name per system configuration
• ~~move GetSessions out of store https://github.com/log2timeline/plaso/pull/3941~~
• SystemConfiguration
  • ~~remove GetSystemConfigurationIdentifier - https://github.com/log2timeline/plaso/pull/3942~~
  • have other artifact attribute containers reference system configuration / source volume they belong to ?