Cache state in memory on writes, read from memory
in reads.
kubestore was previously always reading state from a Secret.
This change should fix bugs caused by temporary loss of access
to kube API server and imporove overall performance
Fixes#7671
Updates tailscale/tailscale#12079,tailscale/tailscale#13900
Signed-off-by: Maisem Ali <maisem@tailscale.com>
Signed-off-by: Irbe Krumina <irbe@tailscale.com>
Co-authored-by: Maisem Ali <maisem@tailscale.com>