lisa.notebook: Add _hv_set_backend() context manager
lisa.notebook: Add _hv_set_backend() context manager

Helper context manager to Work around:
https://github.com/holoviz/holoviews/issues/4962

ARM-software/lisa,ARM-software/lisa,credp/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa,credp/lisa,credp/lisa