NBT path structure

[fdfdjfk3]

Description

this adds functionality for parsing NBT paths

Describe the changes you've made. Link to any issues this PR fixes or addresses. The changes I have made so far implement an NbtPath structure and a parser from a String to an NbtPath. (from this issue) https://github.com/valence-rs/valence/issues/338

this is not fully complete: i have a few questions i need a bit of clarification on:

• Should I still store spans in the enum variants of NbtPathNode? or is that just redundant because I'm already storing owned values (mainly because of escape characters in quoted strings)
• What other types should be able to convert into NbtPath besides String? (like &str?)
• From the original issue: "Once the NbtPath is parsed, lookups can be performed on &Compound or &mut Compound values." -- how should I go about implementing this? i'm having trouble visualizing the structure of a large Compound with many parts and how i'd traverse through it

soo yea that's all for now :p