Global Environment Variables

In general is there a way to use access enviornment variables when paths need to be configured, something like $PROJECT_DIR$ ?

For example: In Settings > "Languages & Frameworks" > Dart I'm asked to enter the "Dart SDK path", what I'd like to do is set a "Global environment variabe", for instance in a shell script "export DART_SDK=/opt/dartsdk", and then in "Dart SDK path" enter: $DART_SDK$, or some such. Is this possible?

This type of feature is needed so that when I commit .idea/libraries/Dart_SDK.xml into a git repo and someone else checks it out will very likely have the dart-sdk installed at a different location so this needs to be a "variable" not hard-coded to a specific path.