The argument input view class hierarchy is a mess

It's confusing both in code and to the user. It should be refactored into a single class if possible.

Each text field should have a descriptive placeholder detailing what exactly will be accepted or what is expected. Currently, sometimes you don't have to quote strings and other times you do, etc.

Also, it's not clear to me whether `char *` are supported in any way. They should be.