Move electron builds into spotlight package and use a unified build from there

[BYK]

Right now we have a separate electron package which is only used to create electron builds from spotlight package. That said we also create self-contained binaries from spotlight package. Unifying these would improve caching, hopefully remove our dependence on mac-os runners on GHA as now we can sign and notarize macOS packages on Linux. It would also simplify the build process even more.