Add expected fail tests

[lukaswittmann]

Such tests should include

• missing required positional
• missing required optional (?)
• option missing value
• invalid int value
• invalid real value
• invalid logical value
• invalid string choice
• invalid integer choice
• mutex conflict
• required mutex missing
• not_less_than violation
• not_bigger_than violation
• unknown option
• extra positional argument
• unknown subcommand
• removed argument used
• append missing value