[experiments] Add a grpc_generate_one_off_internal_targets hook in the BUILD file (#33307)

This allows us to define and insert internal only targets.

bazel/grpc_build_system.bzl

@@ -540,6 +540,9 @@ def grpc_generate_one_off_targets():
 def grpc_generate_objc_one_off_targets():
     pass
 
+def grpc_generate_one_off_internal_targets():
+    pass
+
 def grpc_sh_test(name, srcs = [], args = [], data = [], uses_polling = True, size = "medium", timeout = None, tags = [], exec_compatible_with = [], exec_properties = {}, shard_count = None, flaky = None, exclude_pollers = [], uses_event_engine = True):
     """Execute an sh_test for every <poller> x <EventEngine> combination
 

src/core/BUILD

@@ -15,6 +15,7 @@
 load(
     "//bazel:grpc_build_system.bzl",
     "grpc_cc_library",
+    "grpc_generate_one_off_internal_targets",
     "grpc_upb_proto_library",
     "grpc_upb_proto_reflection_library",
 )
@@ -5987,3 +5988,5 @@ WELL_KNOWN_PROTO_TARGETS = [
     name = "protobuf_" + target + "_upbdefs",
     deps = ["@com_google_protobuf//:" + target + "_proto"],
 ) for target in WELL_KNOWN_PROTO_TARGETS]
+
+grpc_generate_one_off_internal_targets()

tools/distrib/fix_build_deps.py

@@ -487,6 +487,7 @@ for dirname in [
             'grpc_upb_proto_library': lambda name, **kwargs: None,
             'grpc_upb_proto_reflection_library': lambda name, **kwargs: None,
             'grpc_generate_one_off_targets': lambda: None,
+            'grpc_generate_one_off_internal_targets': lambda: None,
             'grpc_package': lambda **kwargs: None,
             'filegroup': lambda name, **kwargs: None,
             'sh_library': lambda name, **kwargs: None,