[ty] Rename type_api => ty_extensions (#19523)

Author: sharkdp

crates/ty_python_semantic/resources/mdtest/call/function.md

@@ -625,7 +625,7 @@ len()
 len([], 1)
 ```
 
-### Type API predicates
+### Type property predicates
 
 ```py
 from ty_extensions import is_subtype_of

crates/ty_python_semantic/resources/mdtest/snapshots/type_api.md_-_Type_API_(`ty_extens…_-_Diagnostic_snapshots_(be112fd8b8cfdc28).snap renamed to crates/ty_python_semantic/resources/mdtest/snapshots/ty_extensions.md_-_`ty_extensions`_-_Diagnostic_snapshots_(662547cd88c67f9f).snap

@@ -3,8 +3,8 @@ source: crates/ty_test/src/lib.rs
 expression: snapshot
 ---
 ---
-mdtest name: type_api.md - Type API (`ty_extensions`) - Diagnostic snapshots
-mdtest path: crates/ty_python_semantic/resources/mdtest/type_api.md
+mdtest name: ty_extensions.md - `ty_extensions` - Diagnostic snapshots
+mdtest path: crates/ty_python_semantic/resources/mdtest/ty_extensions.md
 ---
 
 # Python source files

crates/ty_python_semantic/resources/mdtest/type_api.md renamed to crates/ty_python_semantic/resources/mdtest/ty_extensions.md

@@ -1,4 +1,4 @@
-# Type API (`ty_extensions`)
+# `ty_extensions`
 
 This document describes the internal `ty_extensions` API for creating and manipulating types as well
 as testing various type system properties.

crates/ty_python_semantic/src/types/infer.rs

@@ -10124,7 +10124,7 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
                 callable_type
             }
 
-            // Type API special forms
+            // `ty_extensions` special forms
             SpecialFormType::Not => {
                 let arguments = if let ast::Expr::Tuple(tuple) = arguments_slice {
                     &*tuple.elts