[Fizz] Allow an action provide a custom set of props to use for progressive enhancement (#26749)

Stacked on top of #26735.

This allows a framework to add a `$$FORM_ACTION` property to a function.
This lets the framework return a set of props to use in place of the
function but only during SSR. Effectively, this lets you implement
progressive enhancement of form actions using some other way instead of
relying on the replay feature.

This will be used by RSC on Server References automatically by
convention in a follow up, but this mechanism can also be used by other
frameworks/libraries.