feat: create "transformation pipelines'

[brent-hoover]

One of the cool features that Reaction had that I believe @aldeed came up with is the way that you could use functionsOfType to define a "pipeline" of functions that, for example, a cart might flow through on placeOrder so any plugin could insert itself into that to apply a discount for example.

I think we should reimplement it but possibly make it more explicit. Some ideas might be:

• Create a separate 'pipeline' object separate from functions of type where you could declare a named pipeline and then have methods on that.
• Allow functions to insert themselves as more explicit places like "last" or "first"
• Allow plugins to remove another entry in the pipeline or replace an existing one
• Use decorators to be able to add a pipeline to a method
• Allow a function to cleanly abort a pipeline and have the calling method catch the error
• ???