Migrate CLI of Pharo launcher to use refactored version of CLAP

[Bajger]

Describe the request Currently, CLI interface of launcher uses original CLAP. Purspose is to use updated version which consists of several improvements. These are:

• simplified specification of flags and arguments and overall command specification
• getting instance of clap command from context without executing it (for purposes of tests)

Expected behavior CLI works as expected (all tests green).

Expected development cost Replace all occurences of flags spec and positional with new approach. Rafactor command specification with new approach. Refactor unit tests to use instance of command from spec, instead of doing explicit match and assigning to command.