Allow cjs in serverBuildPath

[morriq]

What version of Remix are you using?

1.7.6

Steps to Reproduce

I have express server written in mjs. I tried to load server bundle created in remix but can't since it does not have cjs extension.

Renaming manually build/index.js to build/index.cjs works well.

Expected Behavior

I should be able to change serverBuildPath in remix.config.mjs to cjs extension

Actual Behavior

setting serverBuildPath to cjs extension has no effect. Actually it has - it stopped creating any bundle.