fix: omit duplicates from list of bundled functions

[eduardoboucas]

Summary

When printing the list of bundled functions, Netlify Build uses zip-it-and-ship-it's listFunctions method, which includes functions that have not been bundled due to a naming conflict (e.g. when both function.js and function.ts are found). Because of this, Netlify Build was incorrectly reporting that both functions were bundled, when in fact only function.js was.

This PR removes those duplicate functions from the list.

Fixes #3974.

A picture of a cute animal (not mandatory, but encouraged)

[ehmicky]

@eduardoboucas What's the latest status of this PR? Should it be closed?

[eduardoboucas]

Sorry, my bad. This fell between the cracks. I'm updating the branch and will merge this later today.