Reduce memory copy in BytesStore

This is derived from LUCENE-10627(https://github.com/apache/lucene/pull/987) AND LUCENE-10657(https://github.com/apache/lucene/pull/1034)

The abstract method copyBytes in DataOutput have to copy from input to a copyBuffer and then write into BytesStore.blocks, which is called in FST initialization read from metaIn. 

Although, this copy bytes only a few bytes (in the testscase only 3-10 bytes), i think we can save this memory copy, just save the DataOutput.copyBytes to create new copyBuffer with 16384 bytes