change settings interface

[JosiasAurel]

addresses #1383

$ mise settings
  List all settings

$ mise settings a
  Get the value of setting with name 'a'

$ mise settings a=b
  Set setting with name 'a' to 'b'

[camsteffen]

I think it would be simpler if the setting value is a separate argument instead of using =? This is how git config works. - mise settings set x value

[jdx]

@camsteffen I want to support both styles, but this matches how mise set works for consistency

[camsteffen]

Sorry I meant mise settings x value. Would that work?

[jdx]

ah yeah, that could be done I think

[jdx]

closing due to inactivity, feel free to reopen if you'd like to work on it more