wgengine/netlog: stop using netmap.NetworkMap type, use LocalBackend

The Logger previously took a *netmap.NetworkMap at Startup and on every
ReconfigNetworkMap call, denormalizing it into per-IP and self lookup
maps. That denormalization is O(n) over all peers and ran on every
netmap update, contributing to the broader quadratic behavior we want
to eliminate when a single peer is added or removed.

Instead, this makes netlog ask LocalBackend (well, nodeBackend) for
the info it needs, letting us remove the netmap.NetworkMap type
entirely from the netlog package.

This is a dependency to removing the netmap.NetworkMap type from
upstream callers, like wgengine.Engine in general.

Updates #12542

Change-Id: Ib5f2de96e788a667332c0a6f7ac833b3d0053b5c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/k8s-operator/depaware.txt

@@ -919,7 +919,7 @@ tailscale.com/cmd/k8s-operator dependencies: (generated by github.com/tailscale/
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/filter/filtertype                     from tailscale.com/types/netmap+
      💣 tailscale.com/wgengine/magicsock                             from tailscale.com/ipn/ipnlocal+
-        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine
+        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine+
         tailscale.com/wgengine/netstack                              from tailscale.com/tsnet
         tailscale.com/wgengine/netstack/gro                          from tailscale.com/net/tstun+
         tailscale.com/wgengine/router                                from tailscale.com/ipn/ipnlocal+

cmd/tailscaled/depaware-min.txt

@@ -194,7 +194,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/filter/filtertype                     from tailscale.com/types/netmap+
      💣 tailscale.com/wgengine/magicsock                             from tailscale.com/ipn/ipnlocal+
-        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine
+        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine+
         tailscale.com/wgengine/netstack/gro                          from tailscale.com/net/tstun+
         tailscale.com/wgengine/router                                from tailscale.com/cmd/tailscaled+
         tailscale.com/wgengine/wgcfg                                 from tailscale.com/ipn/ipnlocal+

cmd/tailscaled/depaware-minbox.txt

@@ -215,7 +215,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/filter/filtertype                     from tailscale.com/types/netmap+
      💣 tailscale.com/wgengine/magicsock                             from tailscale.com/ipn/ipnlocal+
-        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine
+        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine+
         tailscale.com/wgengine/netstack/gro                          from tailscale.com/net/tstun+
         tailscale.com/wgengine/router                                from tailscale.com/cmd/tailscaled+
         tailscale.com/wgengine/wgcfg                                 from tailscale.com/ipn/ipnlocal+

cmd/tailscaled/depaware.txt

@@ -503,7 +503,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/filter/filtertype                     from tailscale.com/types/netmap+
      💣 tailscale.com/wgengine/magicsock                             from tailscale.com/ipn/ipnlocal+
-        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine
+        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine+
         tailscale.com/wgengine/netstack                              from tailscale.com/cmd/tailscaled
         tailscale.com/wgengine/netstack/gro                          from tailscale.com/net/tstun+
         tailscale.com/wgengine/router                                from tailscale.com/cmd/tailscaled+

cmd/tsidp/depaware.txt

@@ -317,7 +317,7 @@ tailscale.com/cmd/tsidp dependencies: (generated by github.com/tailscale/depawar
         tailscale.com/wgengine/filter                                from tailscale.com/control/controlclient+
         tailscale.com/wgengine/filter/filtertype                     from tailscale.com/types/netmap+
      💣 tailscale.com/wgengine/magicsock                             from tailscale.com/ipn/ipnlocal+
-        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine
+        tailscale.com/wgengine/netlog                                from tailscale.com/wgengine+
         tailscale.com/wgengine/netstack                              from tailscale.com/tsnet
         tailscale.com/wgengine/netstack/gro                          from tailscale.com/net/tstun+
         tailscale.com/wgengine/router                                from tailscale.com/ipn/ipnlocal+