Reevaluate the use of log4j within the deegree project

[copierrj]

Given that we do not use most of the functionality of log4j we should discussing moving to a less complicated logging framework.

[tfr42]

Currently the API of slf4j is used in deegree. See what slf4j is offering on options:

[tfr42]

List of logging APIs (incomplete):

• Apache Log4J 2: https://logging.apache.org/log4j/2.x/
• Apache Commons Logging (JCL): https://commons.apache.org/proper/commons-logging/
• SLF4J: http://www.slf4j.org/
• Logback: http://logback.qos.ch/
• Tinylog/Tinylog 2: https://tinylog.org/
• java.util.logging (JUL): https://docs.oracle.com/en/java/javase/11/docs/api/java.logging/java/util/logging/package-summary.html

[tfr42]

Adding a chapter to the documentation how to swap the logging framework and how to build a WAR using an individual Maven POM shall be added.

[tfr42]

Log4j 1.2 has been reloaded into https://reload4j.qos.ch/ which provides an updated version of the old log4j 1.2 API.

[tfr42]

The TMC has the notion to move from Apache Log4j2 Version 2.x to logback as the default logging provider for the deegree 3.5 line.
The handbook shall include a short description how to replace logback with the prefered logging framework by users.