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.*}

Inizia con la classe org.apache.parquet.Log e individua i suoi usi attuali nel progetto. Leggi la documentazione di migrazione collegata prima di modificare l’approccio al logging. Il lavoro è completato quando la classe Log è deprecata e gli usi attuali sono stati sostituiti direttamente con SLF4J.

Scritto dal modello di indicizzazione a partire dal testo della issue.