Add functionality which allows select the flags type

### Add the flags type
- `Int`
- `String`
- `Bool`
- `IntArray`
- `StringArray`
- `BoolArray`

### For example
`cli::Flag("flagName", "flagShortName", description", true, true, "String")`
`cli::Flag("flagName", "flagShortName", description", true, true, "BoolArray[2]")`