Implement strings.format in CEL string extensions.

PiperOrigin-RevId: 958621592

Author: maskri17

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -115,9 +115,6 @@ _TESTS_TO_SKIP_LEGACY = [
 
     # Skip until fixed.
     "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
-    # TODO: Add strings.format.quote.
-    "string_ext/format",
-    "string_ext/format_errors",
 
     # Future features for CEL 1.0
     # TODO: Strong typing support for enums, specified but not implemented.
@@ -143,10 +140,6 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
-    # TODO: Add strings.format.
-    "string_ext/format",
-    "string_ext/format_errors",
-
     # TODO: This is actually a user experience degradation.
     # Not worth fixing until we see a concrete need.
     "basic/functions/unbound_is_runtime_error",

extensions/src/main/java/dev/cel/extensions/BUILD.bazel

@@ -89,7 +89,12 @@ java_library(
         "//checker:checker_builder",
         "//common:compiler_common",
         "//common/internal",
+        "//common/internal:comparison_functions",
+        "//common/internal:date_time_helpers",
         "//common/types",
+        "//common/types:type_providers",
+        "//common/values",
+        "//common/values:cel_byte_string",
         "//compiler:compiler_builder",
         "//extensions:extension_library",
         "//runtime",