Add an option to allow retrieving the IDP metadata from a URL and
keeping the metadata auto-updated on charm hook execution.
Change-Id: I65b20e52835497a3fe57571794f332b2b4327fba
Signed-off-by: Yanos Angelopoulos <yanos@admin.grnet.gr>
Co-authored-by: Stamatis Katsaounis <skatsaounis@admin.grnet.gr>
Co-authored-by: Dmitrii Shcherbakov <dmitrii.shcherbakov@canonical.com>