Multi-Process (primary and secondary) support for Capsule application(s)

## Background

As part of re-thinking our runtime model and pipeline scheduling (#75), we'd like to support [multi-process](https://doc.dpdk.org/guides/prog_guide/multi_proc_support.html) applications, including examples with a non-Capsule DPDK application acting as primary while a Capsule application acts as secondary process or vice versa, as well as two Capsule applications acting as primary and secondary.

One example idea would involve a non-capsule primary DPDK application (e.g maybe [testpmd](https://doc.dpdk.org/guides/testpmd_app_ug/)) that generates packets and forwards those packets to a secondary Capsule-written NF. Another is a primary Capsule application forwarding packets to a [DPDK pdump](https://doc.dpdk.org/guides/howto/packet_capture_framework.html) secondary process. One caveat here is be aware that both processes need to share the same DPDK versions.

A main use case we've seen usually revolves around Open vSwitch being the primary process with other secondary process in something like Capsule, etc...

Start with the DPDK multi-process support guide and the runtime-model and pipeline-scheduling work in #75; compare the testpmd, DPDK pdump, and Open vSwitch primary/secondary scenarios described here. Done means the supported primary and secondary combinations are defined and demonstrated for Capsule and non-Capsule applications, with the shared DPDK-version requirement accounted for.

Written by the indexing model from the issue text.