[java] Adding ability to load a model from a memory mapped byte buffer (#20062)
### Description
Adds support for constructing an `OrtSession` from a
`java.nio.ByteBuffer`. These buffers can be memory mapped from files
which means there doesn't need to be copies of the model protobuf held
in Java, reducing peak memory usage during session construction.
### Motivation and Context
Reduces memory usage on model construction by not requiring as many
copies on the Java side. Should help with #19599.