Port ignore deprecations to 4.9 (#52419)

src/compiler/commandLineParser.ts

@@ -1355,7 +1355,12 @@ namespace ts {
             description: Diagnostics.Control_what_method_is_used_to_detect_module_format_JS_files,
             category: Diagnostics.Language_and_Environment,
             defaultValueDescription: Diagnostics.auto_Colon_Treat_files_with_imports_exports_import_meta_jsx_with_jsx_Colon_react_jsx_or_esm_format_with_module_Colon_node16_as_modules,
-        }
+        },
+        {
+            name: "ignoreDeprecations",
+            type: "string",
+            defaultValueDescription: undefined,
+        },
     ];
 
     /* @internal */

tests/baselines/reference/config/showConfig/Shows tsconfig for single option/ignoreDeprecations/tsconfig.json

@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "ignoreDeprecations": "someString"
+    }
+}