scala-cli fmt and other commands defaults

[romanowski]

Currently, scala-cli formats the current directory when no inputs are given. This stick to the scalafmt defaults but breaks pattern known from other commands (like run or compile) when inputs are always needed.

Should we add . by default to fmt command (as we are doing it now) or stick to the pattern known from other commands? Maybe we should

[bjornregnell]

I guess it is easy to forget the dot after any command. I'd suggest to assume a missing arg means . on any command, but consistency is more important IMO. So I think we need to choose either to infer . in all commands if no args given or always require explicit . in all commands (the latter is a bit "boilerplaty" and the dot might be crytpic to a beginner).