Vite: Support runStep in Vite builder SSv6

[IanVS]

Issue: N/A

Ref: #18555 (comment)

What I did

Support for runStep in story store v6 was added to the Webpack builder, but not Vite. This adds it to vite as well, and cleans up some conditional calls which were necessary before. Previously, we didn't have any guarantee which version of storybook the builder was being used with. Now that it's in the monorepo, it'll be versioned together with the rest of storybook.

How to test

CI, though I'm not sure there are any step functions being executed in tests, or else the Vite builder would have failed previously, I think...

[tmeasday]

CI, though I'm not sure there are any step functions being executed in tests, or else the Vite builder would have failed previously, I think..

The default implementation of runStep is to just run it 🤷. The one exported by the interactions addon additionally adds instrumentation so it shows up nicely in the debugger, so I guess we would need to check a story in the vite builder. We do have some, let's see if we can find it...

[tmeasday]

We don't (currently) have a v6 sandbox using vite (we plan to address this!) so there's no artifact I can point at, but in order to check, I advise running a vite sandbox, setting SSv6, and visiting this story: http://localhost:6006/?path=/story/addons-interactions-basics--step and checking the step works.

Actually it was erroring on next:

[tmeasday]

Awesome!