When the cache options are configured with DefaultNamespaces which
include an entry with `cache.AllNamespaces`, listing from the cache
should fallback to the global cache if there are no namespace-specific
caches that match the namespace from the list options.

Signed-off-by: Joe Lanford <[email protected]>

…3126-to-release-0.19

[release-0.19] 🐛 fix: cache should list out of global cache when present and necessary

We have a scheme write lock but plenty of other codeptaths that read
from the scheme and that don't do looking, resulting in dataraces if the
two happen in parallel.

This change introduces a simple RW lock and makes the fakeclient acquire
read locking for all its operations except when needing the write lock.
This isn't particularly smart, but given that we only have one codepath
that writes to the scheme, it seems good enough.

…3143-to-release-0.19

[release-0.19] 🐛 Fakeclient: Fix dataraces when writing to the scheme

This reverts commit fc48583.

This change breaks some users.

…3147-to-release-0.19

[release-0.19] 🐛 Revert "✨ Expose all Go runtime metrics"