Fixes some of #6662
Issues addressed:
- `ide watch` and `gui watch` should now use the desktop platform
- error screen should now be shown when passing invalid options
- password (both creating password when registering, and resetting password) should now warn on invalid input
# Important Notes
Instead of checking whether `location.hostname === 'localhost'`, I've opted to use a constant defined by the build tool instead. This is to make it easier to merge the cloud IDE and desktop IDE entrypoints in the future, since it would be able to simply set `platform: Platform.cloud` in the build config.
