Adding remaining string ext functions

PiperOrigin-RevId: 807720234

Author: maskri17

common/BUILD

@@ -633,6 +633,7 @@ cc_library(
         ":value_kind",
         "//base:attributes",
         "//common/internal:byte_string",
+        "//common/internal:reference_count",
         "//eval/internal:cel_value_equal",
         "//eval/public:cel_value",
         "//eval/public:message_wrapper",
@@ -713,6 +714,7 @@ cc_test(
         "//internal:testing_descriptor_pool",
         "//internal:testing_message_factory",
         "//runtime:runtime_options",
+        "//runtime/internal:errors",
         "@com_google_absl//absl/base:core_headers",
         "@com_google_absl//absl/base:nullability",
         "@com_google_absl//absl/functional:function_ref",