feat: add item predicate syntax and inline loot arguments

[misode]

This PR adds support for the new item predicate syntax.

*[custom_data~{gm4_metallurgy:{stored_shamir:"lumos"}},damage|!max_item_stack=1]

I would like some feedback, mostly on the AST structure and maybe on the parser (could it be split up, does it need anything special to support multiline?)

Also the tests are failing, probably because I changed the AST result of the item_predicate format, it's no longer an AstItem, but now an AstItemPredicate. Would it be better to have a single AST that supports both?

[RitikShah]

Did you make AstItemPredicate represent both what AstItem and the new inline predicates do now? I'm a bit confused, isn't inline predicates an alternative to the previous way, so shouldn't it be a union of both things, or is this what you are asking about.

[misode]

Yeah that's the bulk of the problem. The issue is that item predicates allow a complex syntax including |, ~, etc. Item predicates need to be able to represent this complex structure. Maybe components in AstItem could be a Union[AstItemComponents, AstItemComponentsGroup]

[misode]

I'm happy with the PR now. Feel free to review @vberlier @RitikShah

[RitikShah]

I'm not as familiar with the Mecha codebase but this implementation from the last commit seems cleaner.

[RitikShah]

I don't really understand this implementation. what's with sep and comma here?

[RitikShah]

ohh, it's just adjusting what's outputted based on how many items need to be outputted..

[misode]

I mostly took this from self.collection, but that always requires some kind of surrounding brackets and uses commas as separators, which was too limiting

[vberlier]

After looking at the PR and investigating the official changelog I thought it would probably be more useful down the line if we split AstItem into separate node types AstItemStack and AstItemPredicate, so that's what I did and released in v0.93.0. The final design ended up quite similar to your first commit actually. I couldn't merge as-is but your changes served as a great starting point, thanks again for the help!