Rollup merge of #79951 - LeSeulArtichaut:ty-ir, r=nikomatsakis

Refractor a few more types to `rustc_type_ir`

In the continuation of #79169, ~~blocked on that PR~~.

This PR:
 - moves `IntVarValue`, `FloatVarValue`, `InferTy` (and friends) and `Variance`
 - creates the `IntTy`, `UintTy` and `FloatTy` enums in `rustc_type_ir`, based on their `ast` and `chalk_ir` equilavents, and uses them for types in the rest of the compiler.

~~I will split up that commit to make this easier to review and to have a better commit history.~~
EDIT: done, I split the PR in commits of 200-ish lines each

r? `````@nikomatsakis````` cc `````@jackh726`````

1 files changed, 8 insertions, 12 deletions

diff --git a/compiler/rustc_codegen_ssa/src/mir/block.rs b/compiler/rustc_codegen_ssa/src/mir/block.rs
index ecac05fd955..c8219081678 100644
--- a/compiler/rustc_codegen_ssa/src/mir/block.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/block.rs
@@ -875,20 +875,16 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             ty::Uint(_) => value.to_string(),
                             ty::Int(int_ty) => {
                                 match int_ty.normalize(bx.tcx().sess.target.pointer_width) {
-                                    ast::IntTy::I8 => (value as i8).to_string(),
-                                    ast::IntTy::I16 => (value as i16).to_string(),
-                                    ast::IntTy::I32 => (value as i32).to_string(),
-                                    ast::IntTy::I64 => (value as i64).to_string(),
-                                    ast::IntTy::I128 => (value as i128).to_string(),
-                                    ast::IntTy::Isize => unreachable!(),
+                                    ty::IntTy::I8 => (value as i8).to_string(),
+                                    ty::IntTy::I16 => (value as i16).to_string(),
+                                    ty::IntTy::I32 => (value as i32).to_string(),
+                                    ty::IntTy::I64 => (value as i64).to_string(),
+                                    ty::IntTy::I128 => (value as i128).to_string(),
+                                    ty::IntTy::Isize => unreachable!(),
                                 }
                             }
-                            ty::Float(ast::FloatTy::F32) => {
-                                f32::from_bits(value as u32).to_string()
-                            }
-                            ty::Float(ast::FloatTy::F64) => {
-                                f64::from_bits(value as u64).to_string()
-                            }
+                            ty::Float(ty::FloatTy::F32) => f32::from_bits(value as u32).to_string(),
+                            ty::Float(ty::FloatTy::F64) => f64::from_bits(value as u64).to_string(),
                             _ => span_bug!(span, "asm const has bad type {}", ty),
                         };
                         InlineAsmOperandRef::Const { string }