VSCode ESP-IDF extension selected project configuration forgotten

[cskilbeck]

I've defined two project configurations ('debug', 'release') using the 'ESP-IDF Open Project Configuration' page.

It has created `esp_idf_project_configuration.json` and all is well, I can select a project configuration from the status bar and it uses the values specified in `esp_idf_project_configuration.json`

But when I quit and restart VSCode, neither of them is selected, so if I forget to select one and build, I get a build which is neither debug or release. How can I make VSCode remember the last project configuration?