Workflow Versioning

[WhitWaldo]

In light of the discussion around variations of workflow re-runs and the community ask for versioning, I wanted to introduce a new proposal that marries @JoshVanL 's Rerun from Activity proposal to a versioning migration scheme that addresses the issue I raised in one of the comments regarding base type inconsistency in running ad-hoc workflows against versioned underlying types.

I've gone through a couple iterations of this with others and this is the most recent version of the idea. Because the runtime isn't familiar with the type implementations of the workflows themselves in the application, this instead leans more on minor state changes on the workflow actor and changes to workflow resolution at the SDKs themselves than the runtime. At some point, following some feedback on this, I'd like to move ahead with a POC to prove out the concept, but I wanted to toss it out there first to see if I'm missing anything really obvious.

I've written this proposal assuming that we're wanting to move forward with both the Multi-App Workflows and the Rerun from Activity proposals to accommodate both in a way that enables all three concepts.

Thank you for the consideration!

[olitomlinson]

Generally support this proposal as it seems to offer some basic but useful versioning capabilities that people can easily grok.

Great to see the actual end-user Developer experience thoughtfully considered.