Add version of Scala to the output of `scala-cli --version`

[romanowski]

Is your feature request related to a problem? Please describe.

Getting the version of the launcher is important mainly for advanced users; beginners would expect to see a version of Scala used.

See more in the @julienrf comment: scala/improvement-proposals#46 (comment)

Describe the solution you'd like
When running scala-cli --version the default version of Scala is printed as well as the version of the launcher. With a provided argument (e.g. scala-cli --version .), the version of Scala as configured in the argument should be provided.

Describe alternatives you've considered
A dedicated command/argument to print Scala version.

[bjornregnell]

Good!
And it would be helpful and good UX / DX if all these worked:

scala-cli -v
scala-cli --version
scala-cli -version
scala-cli version

(but not as critical as with all variants of scala-cli help, as the help command hopefully explains how to use the version command...)

[lwronski]

If we change behaviours of command scala-cli --version, it needs to be updated logic in update command, because there we run scala-cli --version command to find out which version of Scala Cli is already installed.