With #5516 we added a way to have debug sessions automatically launched at startup, or when a special file was created.

For some uses of this, it would be better to keep it out of the tree (for example in the case where an IDE like Firebase Studio wants to use it to auto-connect to an existing session without polluting the users workspace with the temporary file).

One way to achieve this is to support an environment variable to override the location of this folder. For example:

SET DART_CODE_CONFIGURATION_PATH=/tmp/xyz123/.dart_code

Then when we load, we'll use this environment variable in place of .dart_code/ when looking for (and setting up a watcher for) the auto-launch file.

If the variable is set and is a relative path, then we will look for it in all workspaces (as we do with .dart_code by default). This means if you wanted to just rename or relocate the folder inside the tree you could, but if it's an absolute path then we will look for one (not per-workspace folder).