Get meson examples working with bzlmod

Note that a newer version of pkgconfig than that installed in ubuntu 20
must be used to build libxau, therefore the built_pkgconfig_toolchain is
now registered

MODULE.bazel

@@ -16,6 +16,7 @@ use_repo(
     "cmake_3.23.2_toolchains",
     "cmake_src",
     "gnumake_src",
+    "meson_src",
     "ninja_1.11.1_toolchains",
     "ninja_build_src",
     "pkgconfig_src",
@@ -31,6 +32,8 @@ register_toolchains(
     "@rules_foreign_cc_framework_toolchain_macos//:toolchain",
     "@rules_foreign_cc_framework_toolchain_windows//:toolchain",
     "@rules_foreign_cc//toolchains:built_make_toolchain",
+    "@rules_foreign_cc//toolchains:built_meson_toolchain",
+    "@rules_foreign_cc//toolchains:built_pkgconfig_toolchain",
     "@rules_foreign_cc//toolchains:preinstalled_autoconf_toolchain",
     "@rules_foreign_cc//toolchains:preinstalled_automake_toolchain",
     "@rules_foreign_cc//toolchains:preinstalled_m4_toolchain",

examples/MODULE.bazel

@@ -7,11 +7,44 @@ local_path_override(
 tools = use_extension("@rules_foreign_cc//foreign_cc:extensions.bzl", "tools")
 tools.cmake(version = "3.23.1")
 tools.ninja(version = "1.11.1")
+use_repo(
+    tools,
+    "meson_src",
+)
 
 bazel_dep(name = "platforms", version = "0.0.6")
 bazel_dep(name = "rules_swift", version = "1.6.0", repo_name = "build_bazel_rules_swift")
 bazel_dep(name = "rules_apple", version = "2.1.0", repo_name = "build_bazel_rules_apple")
 bazel_dep(name = "apple_support", version = "1.4.1", repo_name = "build_bazel_apple_support")
+bazel_dep(name = "rules_python", version = "0.22.0")
+
+python = use_extension("@rules_python//python/extensions:python.bzl", "python")
+python.toolchain(
+    name = "python3_9",
+    python_version = "3.9",
+)
+use_repo(python, "python3_9")
+use_repo(python, "python3_9_toolchains")
+
+register_toolchains(
+    "@python3_9_toolchains//:all",
+)
+
+interpreter = use_extension("@rules_python//python/extensions:interpreter.bzl", "interpreter")
+interpreter.install(
+    name = "interpreter_python3_9",
+    python_name = "python3_9",
+)
+use_repo(interpreter, "interpreter_python3_9")
+
+pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
+pip.parse(
+    name = "pip",
+    python_interpreter_target = "@interpreter_python3_9//:python",
+    requirements_lock = "//:requirements_lock.txt",
+    requirements_windows = "//:requirements_windows.txt",
+)
+use_repo(pip, "pip")
 
 # bazel_dep(name = "rules_android", version = "0.1.1")
 # bazel_dep(name = "rules_jvm_external", version = "5.1")