[Feature Request] Remove all thread locals from the codebase

[bergundy]

Even though there's an assumption that the generator runs in a single thread, these thread locals are a code smell, and were likely introduced by a model that was taking shortcuts.

nexgen/src/generator/json_schema/python.rs

Line 108 in 5631b32

thread_local! {

nexgen/src/generator/json_schema/typescript.rs

Line 32 in 5631b32

thread_local! {