[nrf noup] Include pigweed_environment.gni in tree

pigweed_environment.gni file is included by GN scripts
used by Matter build system. The file is generated by
bootstrap.sh script but in nRF Connect SDK we do not want
to force user to run that script. Therefore, include a copy
of that file in tree.

Signed-off-by: Damian Krolik <damian.krolik@nordicsemi.no>

Author: Damian-Nordic

build_overrides/pigweed_environment.gni

@@ -0,0 +1,9 @@
+# This file is automatically generated by Pigweed's environment setup. Do not
+# edit it manually or check it in.
+declare_args() {
+  pw_env_setup_CIPD_PYTHON = "//.environment/cipd/packages/python"
+  pw_env_setup_CIPD_PIGWEED = "//.environment/cipd/packages/pigweed"
+  pw_env_setup_CIPD_ARM = "//.environment/cipd/packages/arm"
+  pw_env_setup_VIRTUAL_ENV = "//.environment/pigweed-venv"
+  pw_env_setup_PACKAGE_ROOT = "//.environment/packages"
+}