fix: Replace spaces in package directory name with a hyphen

[felixrieseberg]

If your app's name contains a space, the temporary package directory will also contain a space. That works fine for everything Electron and Node, but if you have a native module that uses the classic gyp/make combo, paths with spaces are not allowed and things will break. An earlier filenamify does not replace spaces because spaces are generally legal, they just break (some) native module builds.

With this PR, spaces in your app name in packageDir will be replaced with a -, just the same we replace other special characters.

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Summarize your changes: fix: Don't create package directories with spaces

[BlackHole1]

LGTM

[felixrieseberg]

One thing that's really important here: This won't work without also changing electron-packager, which would be a breaking change.

I'm taking a look at that, too.

[erikian]

@felixrieseberg I'm adding the breaking-change label so we can keep track of those — feel free to remove it if it's not the case!

[felixrieseberg]

Totally fair, but great news: We can fix this here (electron/packager#1585) without breaking forge!