setup lang picker in right space so it works on core docs (#6669)
setup lang picker in right space so it works on core docs (#6669)

* setup lang picker in right space so it works on core docs

* also don't crash from missing pxt

* need to defer langpicker until ksRunnerReady

* modalContainer scope

Microsoft/pxt,Microsoft/pxt,Microsoft/pxt,Microsoft/pxt,Microsoft/pxt