Receive-processors v0.4.0

Added

• Processors now have access to a Storage class that allows them to define the files they will create. In production deployments this class will be backed
  by the SDP metadata library, which ensures files are created in the correct location, and they are recorded in a metadata file.

Changed

• Switched project build from setuputils to Poetry
• Ensured processors successfully disconnect from the Plasma Store when they finish.
• Updated dependency on receive-modules to 3.6.0.
• Updated dependency on cbf-emulator to 4.2.0.
• Changed MSWriterProcessor to use new Storage class.