This PR changes tags to be something that exists on nodes in addition to users, to being its own thing. It is part of moving our tags support towards the correct tailscale compatible implementation.
There are probably rough edges in this PR, but the intention is to get it in, and then start fixing bugs from 0.28.0 milestone (long standing tags issue) to discover what works and what doesnt.
Updates #2417Closes#2619
Initial work on a nodestore which stores all of the nodes
and their relations in memory with relationship for peers
precalculated.
It is a copy-on-write structure, replacing the "snapshot"
when a change to the structure occurs. It is optimised for reads,
and while batches are not fast, they are grouped together
to do less of the expensive peer calculation if there are many
changes rapidly.
Writes will block until commited, while reads are never
blocked.
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
