[RFC007] Migrate the typechecker to the new AST - Part I (#2121)

* Copy the code from typechecker, get rid of generic term env

* Switch to bytecode::ast::typ::*, add a whole cargaison of lifetimes

* Move Traverse in its own module

* [WIP] Pass missing allocator to conv functions

* Continue migration of the typechecker to the new AST

* More typecheck conversion, typecheck::operation conversion

* Introduce record-typechecking-related infrastructure

* Some fixes related to term environment populating

* End of first step for record typechecking

* Implement Traverse for various new AST components

* Fix various compiler errors

* Reset unintentional changes to mainline typecheck module

* Fix more compiler errors (remaining: tc::eq and tc::error)

* Migrate type equality to the new AST

* Fix compilation errors in bytecode::typecheck::error

* Fix compilation errors in bytecode::typecheck::subtyping

* Fix compilation errors in bytecode::typecheck::reporting

* Fix more compiler errors

* Update unif to use new TypeEq trait

* Fix compilation errors and warnings

* Fix typo in comment

* Fix clippy errors

* Fix cargo doc warnings

* Fix more clippy warnings

cli/src/doctest.rs

@@ -19,10 +19,8 @@ use nickel_lang_core::{
     label::Label,
     match_sharedterm, mk_app, mk_fun,
     program::Program,
-    term::{
-        make, record::RecordData, LabeledType, RichTerm, Term, Traverse as _, TraverseOrder,
-        TypeAnnotation,
-    },
+    term::{make, record::RecordData, LabeledType, RichTerm, Term, TypeAnnotation},
+    traverse::{Traverse as _, TraverseOrder},
     typ::{Type, TypeF},
     typecheck::TypecheckMode,
 };