jupyter: add environment variable for quarto base format

Note that we already communicate this to the knitr engine via format$pandoc$to. Here we communicate the base-format which enables explicit detection of extended formats like dashboard and email.

Author: jjallaire

src/resources/jupyter/notebook.py

@@ -121,6 +121,9 @@ def build_kernel_options(options):
 
 
 def set_env_vars(options):
+    os.environ["QUARTO_OUTPUT_BASE_FORMAT"] = str(
+        options["format"]["identifier"]["base-format"]
+    )
     os.environ["QUARTO_FIG_WIDTH"] = str(options["fig_width"])
     os.environ["QUARTO_FIG_HEIGHT"] = str(options["fig_height"])
     if options["fig_format"] == "retina":