[reorg] move src/core/lib/config -> src/core/config (grpc#37847)

Closes grpc#37847

COPYBARA_INTEGRATE_REVIEW=grpc#37847 from markdroth:reorg_config 191c546
PiperOrigin-RevId: 698957093

Author: markdroth

BUILD

@@ -2971,10 +2971,10 @@ grpc_filegroup(
 grpc_cc_library(
     name = "load_config",
     srcs = [
-        "//src/core:lib/config/load_config.cc",
+        "//src/core:config/load_config.cc",
     ],
     hdrs = [
-        "//src/core:lib/config/load_config.h",
+        "//src/core:config/load_config.h",
     ],
     external_deps = [
         "absl/flags:flag",
@@ -2992,11 +2992,11 @@ grpc_cc_library(
 grpc_cc_library(
     name = "config_vars",
     srcs = [
-        "//src/core:lib/config/config_vars.cc",
-        "//src/core:lib/config/config_vars_non_generated.cc",
+        "//src/core:config/config_vars.cc",
+        "//src/core:config/config_vars_non_generated.cc",
     ],
     hdrs = [
-        "//src/core:lib/config/config_vars.h",
+        "//src/core:config/config_vars.h",
     ],
     external_deps = [
         "absl/flags:flag",
@@ -3012,15 +3012,15 @@ grpc_cc_library(
 grpc_cc_library(
     name = "config",
     srcs = [
-        "//src/core:lib/config/core_configuration.cc",
+        "//src/core:config/core_configuration.cc",
     ],
     external_deps = [
         "absl/functional:any_invocable",
         "absl/log:check",
     ],
     language = "c++",
     public_hdrs = [
-        "//src/core:lib/config/core_configuration.h",
+        "//src/core:config/core_configuration.h",
     ],
     visibility = ["@grpc:client_channel"],
     deps = [