Deprecate Log and move to SLF4J Logger

The current Log class is intended to allow swapping out logger back-ends, but SLF4J already does this. It also doesn't expose as nice of an API as SLF4J, which can handle formatting to avoid the cost of building log messages that won't be used. I think we should deprecate the org.apache.parquet.Log class and move to using SLF4J directly, instead of wrapping SLF4J (PARQUET-305).

This will require deprecating the current Log class and replacing the current uses of it with SLF4J.

**Reporter**: [Ryan Blue](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=rdblue) / @rdblue
#### Related issues:
- [Fix flush() for RecordConsumer and implementations](https://github.com/apache/parquet-java/issues/1941) (is blocked by)
- [Avoid evoking job.toString() in ParquetLoader](https://github.com/apache/parquet-java/issues/1942) (is blocked by)
- [Shading SLF4J prevents SLF4J locating org.slf4j.impl.StaticLoggerBinder](https://github.com/apache/parquet-format/issues/302) (is related to)
- [Logger instantiated for package org.apache.parquet may be GC-ed](https://github.com/apache/parquet-java/issues/1830) (is related to)
- [Shutdown hook in parquet-avro library corrupts data and disables logging](https://github.com/apache/parquet-java/issues/1916) (is required by)

_{**Note**: *This issue was originally created as [PARQUET-401](https://issues.apache.org/jira/browse/PARQUET-401). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Beginne mit der Klasse org.apache.parquet.Log und ermittle ihre derzeitige Verwendung im gesamten Projekt. Lies die verlinkte Migrationsdokumentation, bevor du den Logging-Ansatz änderst. Als erledigt gilt die Aufgabe, wenn die Klasse Log als veraltet gekennzeichnet ist und die derzeitigen Verwendungen direkt durch SLF4J ersetzt wurden.

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