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ARROW-2645: [Java] Refactor ArrowWriter to remove all ArrowFileWriter specifc logic

Related to #2079 , the DictionaryBatch `ArrowBlock`s were being accumulated in the base class and used by `ArrowFileWriter` but not `ArrowStreamWriter`.  This refactors the `ArrowWriter` to move Lists of ArrowBlocks from the base class to only `ArrowFileWriter`.

Moved tests counting ArrowBlocks written from ArrowStreamWriter tests to ArrowFileWriter.

Author: Bryan Cutler <cutlerb@gmail.com>

Closes #2090 from BryanCutler/java-ArrowStreamWriter-accum-DictionaryBlocks-ARROW-2645 and squashes the following commits:

fc7f061 <Bryan Cutler> added comment about saving ArrowBlocks
5e4711a <Bryan Cutler> Moved lists of ArrowBlocks in ArrowWriter base class to ArrowFileWriter where they are used