mgr/dashboard: Fix various RGW issues
* Fix handling of tenanted users
* Better exception handling if RGW backend is not available
* RGW user/bucket "max. size" should be hidden when "user/bucket quota" is not enabled
* Fix bug in loading user quota.
Fixes: https://tracker.ceph.com/issues/38800
partial manual backport of
61995970916cb11f66c3800bcf869755f8dae32c
partial manual backport of
e6f130d47023c24f8a9c742f145abd34d7320cd8
partial manual backport of
945e790cab57785e1bc2dbf708d5ddafec618aba
partial manual backport of
a98bca6a2f161140f78f34cfa5f5ebec07af2f82
partial manual backport of
975736aba546adb09ce4f38a1ae061621f7240cd
This fix is not cherry-picked because the code was completely re-worked for Nautilus (codebase is too far apart).
Signed-off-by: Volker Theile <vtheile@suse.com>