Update DSL to support using custom log4j.xml file running ATs

[lucassaldanha]

While investigating issues, it would be useful to expand our DSL to support custom log levels that can be defined via the log4j.xml file. Usually, we rely on using the debug_changeLevel endpoint, but it can be tricky to use this option when we need some early log messages.

Ideally, we have the option of creating a custom log4j.xml file via our DSL when creating a test node.

It could look like something like this:

TekuNodeConfigBuilder.createBeaconNode()
        [...]
        .wihtLogLevel("tech.pegasys.teku.spec.logic.common.block.AbstractBlockProcessor", DEBUG)
        .wihtLogLevel("tech.pegasys.teku.spec.logic.common.statetransition.epoch", TRACE)
        [...]
        .build();