[core] Rework slf4j reinitialization

[adangel]

Describe the PR

This is necessary to fix the integration test "MPMD-244-logging" for maven.

• Support also subclasses of slf4j-simple: e.g. maven uses an own logger factory and own loggers
• Determine the new log level by reevaluating the configuration, similar what the constructors did
• Remove unnecessary PmdLoggerFactoryFriend. The reset function is useless, as the logger instances are static fields in the individual classes, so clearing the loggerMap doesn't help.

This change didn't break any existing unit tests, so I assume, the switch between "--debug" and normal logging still works. I've verified it locally with the maven-pmd-plugin that logging can now be enabled/disabled by the plugin.

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)

[pmd-test]

	1 Message
📖	Compared to master: This changeset changes 7 violations, introduces 1 new violations, 0 new errors and 0 new configuration errors, removes 1 violations, 0 errors and 0 configuration errors. Full report

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