Description

@bluwy proposed to remove the top level createEnvironment as it didn't make sense as a default. The types would get more complex though, and after #18465, we can instead make the top-level createEnvironment be client-only instead. This is also interesting because now a single environment could potentially be configured as:

export default defineConfig(electronEnvironment({
  build: {
    outDir: '/app',
  }
}))

Maybe we should recommend the form below, but I think the above is interesting to consider too (it isn't the reason for this PR though).

export default defineConfig({
  build: {
    outDir: '/app',
  },
  environments: {
    client: electronEnvironment()
  }
})