Cleanup

[odisseus]

• Bumped the versions of SBT and its plugins
• Bumped the versions of JS dependencies
• Cleaned some unused imports
• Added a small helper function (this was needed because a compilation error appeared)

I don't know how to test these changes properly, so I checked that at least sbt open works as it should.

[Baccata]

in order to test, you can indeed run the open after a fastOptJS and execute the command provided by the extension to ensure it still works in the development host, that's usually good enough, it's not like the extension changes often enough that it warrants automated tests