def: support --env and --wrapped

[WindSoilder]

I plan to add parser keywords as AstNode variants. I'm not sure if it's a right direction, so here is a small pr about def parsing, it adds env: bool and wrapped: bool as part of a def ast node.

Then these information can be used after parsing.

[ysthakur]

Thanks for the quick changes! Not too familiar with the new parser but this looks simple enough. Let's go for it