[Java] Allow loading/unloading vectors without using FieldNodes

The information stored in FieldNode structure is not strictly necessary for serializing/deserializing vectors. We should allow loading/unloading of vectors without it.

**Reporter**: [Steven Phillips](https://issues.apache.org/jira/browse/ARROW-792) / @StevenMPhillips

_{**Note**: *This issue was originally created as [ARROW-792](https://issues.apache.org/jira/browse/ARROW-792). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Start by tracing the Java vector loading and unloading paths involved in serialization and deserialization, then identify where FieldNode data is required. The work is done when vectors can be loaded and unloaded without a FieldNode structure while preserving the existing serialization behavior.

Written by the indexing model from the issue text.