NIFI-6955 close streams in Reader/writer mock

[IlyaKovalev]

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ArrayListRecordReader (nifi-mock-record-utils) obtain inputStream in own constructor but don't close this.
ArrayListRecordWriter has the same problem with outputStream.
So if in custom processor i use
InputStream in = session.read(flowfile)
reader = factory.createRecordReader(flowfile, in, logger)
reader.close()
Tests fail and complain that file didn't close.

Add streams and close them in close()

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[markap14]

Thanks @IlyaKovalev! I have merged your changes to master.