AVRO-4361: [java] Size collection guards from the writer's schema

[rayokota]

What is the purpose of the change

This PR fixes AVRO-4361: the collection size guard (AVRO-4241, AVRO-4300,
AVRO-4324) rejects valid data when the reader's array element or map value
schema has a larger minimum encoded size than the writer's. Examples are a
field added with a default, int promoted to double, or null read as a
nullable union. The guard computed the minimum from the reader's schema, but
the bytes were written with the writer's schema.

• Fast reader (FastReaderBuilder.createArrayReader): the writer's array
  schema is available as action.writer, so the guard now uses the writer's
  element type. The guard stays exact.

• Classic and reflect readers (GenericDatumReader, ReflectDatumReader):
  only the reader's element schema is available while reading. A new
  minBytesToRead(Schema) keeps the existing exact bound
  (minBytesPerElement) when the writer's and reader's schemas are equal. That
  check is computed once per reader and reset by setSchema / setExpected.
  When the schemas differ, it uses a new minResolvedBytesPerElement: the
  minimum size of any writer's schema that resolves to the reader's.

  • A field with a default counts 0.
  • float and double count 1, since they may be promoted from int or long.
  • A union counts the smaller of 1 and its smallest branch.
  • fixed keeps its size.

  This bound is never larger than the exact one, so a type that was capped as
  zero-byte is still capped. And it is 0 whenever a writer's value could be 0
  bytes, so valid data is never rejected. The zero-byte allocation cap is now
  chosen from the same bound, for arrays and maps.

• When the schemas differ, the classic and reflect guards are looser than the
  exact bound, but still bound a declared count by the bytes remaining.

• ensureAvailableCollectionBytes(Decoder, long, Schema) is unchanged; its
  Javadoc now says to pass the writer's element schema. A protected
  ensureAvailableCollectionBytes(Decoder, long, int) overload is added for
  ReflectDatumReader.

Verifying this change

New tests, each run on both the fast and classic readers where applicable:

• TestGenericDatumReader
  • testMinResolvedBytesPerElement: the resolved bound for promotions,
    unions, fixed, and records with defaulted fields.
  • arrayOfRecordsWithAddedDefaultFieldDecodes: the reported case.
  • arrayWithPromotedElementTypeDecodes: int, long and float read as
    double.
  • mapWithPromotedValueTypeDecodes
  • arrayOfNullsReadAsNullableUnionDecodes
  • resolvedArrayRejectsHugeCount: the guard still rejects a huge declared
    count when resolving.
  • equalSchemasKeepExactBound: equal but distinct schema instances keep the
    exact bound.
• TestReflectDatumReader.read_arrayWithPromotedElementType

Without the fix, the five decode tests fail with the reported
EOFException: Collection claims ... bytes are available.

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable