Fixes in the ability to run jupyter-lab: better startup script & buil…

…d_python support (#31691)

* Fix up jupyter-lab execution environment:

- relative paths for the paa-store were not working and it was hard
  to debug them. Added detection of this error and auto-adjustment
  for the common case of running scripts from a subdir
- added option to build_python to auto-install these requirements.

* Restyle

* Remove unused imports

* Jupyterlab sets name to main ... so make use of it

* make linter happy

* Fix typo

* Remove checkpoint - probably should not have beeen checked in to start with

* Add jupyter temp dir to gitignore

.gitignore

@@ -80,3 +80,7 @@ examples/thermostat/ameba/build
 # https://github.com/espressif/idf-component-manager#using-with-a-project
 examples/*/esp32/managed_components
 examples/*/esp32/dependencies.lock
+
+# jupyter temporary files
+.ipynb_checkpoints
+