Following the prototype processor implementation in #1688, generalize the solution such that configuring the shipper in the agent policy causes all processors to be created in the shipper instead of in the input.

Ensure there are integration and unit tests in the shipper covering all possible permutations of processor configuration. It must be possible to configure any type of processor. Ensure arbitrary number of processors can be configured per input. Ensure the shipper detects and reports errors when it is provided invalid processor configuration.

The exact scope of this issue will be refined once #1688 is completed.