ci: move public-api goldens to goldens directory (#35768)

Moves the public api .d.ts files from tools/public_api_guard to
goldens/public-api.

Additionally, provides a README in the goldens directory and a script
assist in testing the current state of the repo against the goldens as
well as a command for accepting all changes to the goldens in a single
command.

PR Close #35768

packages/compiler-cli/BUILD.bazel

@@ -1,6 +1,6 @@
 package(default_visibility = ["//visibility:public"])
 
-load("//tools:defaults.bzl", "pkg_npm", "ts_library")
+load("//tools:defaults.bzl", "pkg_npm", "ts_api_guardian_test", "ts_library")
 load("@npm_bazel_typescript//:index.bzl", "ts_config")
 
 ts_config(
@@ -59,3 +59,23 @@ pkg_npm(
         "//packages/compiler-cli/ngcc",
     ],
 )
+
+ts_api_guardian_test(
+    name = "error_code_api",
+    actual = "packages/compiler-cli/npm_package/src/ngtsc/diagnostics/src/error_code.d.ts",
+    data = [
+        ":npm_package",
+        "//goldens:public-api",
+    ],
+    golden = "goldens/public-api/compiler-cli/error_code.d.ts",
+)
+
+ts_api_guardian_test(
+    name = "compiler_options_api",
+    actual = "packages/compiler-cli/npm_package/src/ngtsc/core/api/src/public_options.d.ts",
+    data = [
+        ":npm_package",
+        "//goldens:public-api",
+    ],
+    golden = "goldens/public-api/compiler-cli/compiler_options.d.ts",
+)