NIFI-3420 Add Hadoop-readable Lz4 compression

[ilganeli]

• This is an initial contribution of a fix for NIFI-3420
• This code is not yet tested
• Unit tests will be added soon.

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[ilganeli]

I've added unit tests but am closing this issue for now. There is a substantial blocker to this approach since it leverages the classes from Hadoop which themselves depend on natively compiled and loaded C code. Unless NiFi explicitly adds the C-code for the Lz4 codec and manually builds and loads that library, we won't be able to use the Codec in Hadoop.

I've also evaluated using the lz4-java library instead but this does not generate data in a Hadoop readable format.