avro

AVRO-3666 [Java] Use the new schema parser (#2642)

* AVRO-3666: Redo schema parsing code

This undoes the split schema parsing to allow forward references, which
is to be handles by the SchemaParser & ParseContext classes. It uses the
new ParseContext for the classic schema parser to accommodate this.

Next step: use the new SchemaParser and resolve unresolved / forward
references after parsing. This will also resolve "forward" references
that were parsed in subsequent files.

* AVRO-3666: Resolve references after parsing

By resolving references after parsing, we allow both forward references
within a file as between subsequent files.

This change also includes using the new SchemaParser everywhere, as
using it is the best way to flush out bugs.

* AVRO-3666: Remove wrong test

* AVRO-1535: Fix aliases as well

* AVRO-3666: Re-enable disabled test

Also includes changes necessary to debug.

* AVRO-3666: Fix RAT exclusion

The wrong exclusion was removed.

* AVRO-3666: Remove unused field

* AVRO-3666: Introduce SchemaParser.ParseResult

This ensures the SchemaParser never returns unresolved schemata.

* AVRO-3666: Use SchemaParser for documentation

* AVRO-3666: Refactor after review

* AVRO-3666: Fix javadoc

* AVRO-3666: Fix merge bug

* AVRO-3666: Fix CodeQL warnings

* AVRO-3666: Increase test coverage

* AVRO-3666: Fix tests

* AVRO-3666: Refactor schema parsing for readability

The JSON schema parser is quite complex (it is a large method). This
change splits it in multiple methods, naming the various stages.

* AVRO-3666: rename method to avoid confusion

* AVRO-3666: Reduce PR size

This change reduces the PR size, but does require some extra work after
merging: the new SchemaParser class is hardly used, and the (now)
obsolete Schema.Parser class is used heavily.

* AVRO-3666: Reduce PR size more

* AVRO-3666: Reduce PR size again

* AVRO-3666: Spotless

* Update lang/java/avro/src/main/java/org/apache/avro/Schema.java

Co-authored-by: Fokko Driesprong <fokko@apache.org>

* AVRO-3666: Spotless

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Co-authored-by: Fokko Driesprong <fokko@apache.org>