fix: stop spamming DERP map updates for equivalent maps (#11792)

Fixes 2 related issues:

1. wsconncache had incorrect logic to test whether to send DERPMap updates, sending if the maps were equivalent, instead of if they were _not equivalent_.
2. configmaps used a bugged check to test equality between DERPMaps, since it contains a map and the map entries are serialized in random order. Instead, we avoid comparing the protobufs and instead depend on the existing function that compares `tailcfg.DERPMap`. This also has the effect of reducing the number of times we convert to and from protobuf.

tailnet/conn.go

@@ -218,7 +218,7 @@ func NewConn(options *Options) (conn *Conn, err error) {
 		magicConn.DiscoPublicKey(),
 	)
 	cfgMaps.setAddresses(options.Addresses)
-	cfgMaps.setDERPMap(DERPMapToProto(options.DERPMap))
+	cfgMaps.setDERPMap(options.DERPMap)
 	cfgMaps.setBlockEndpoints(options.BlockEndpoints)
 
 	nodeUp := newNodeUpdater(
@@ -326,7 +326,7 @@ func (c *Conn) SetNodeCallback(callback func(node *Node)) {
 
 // SetDERPMap updates the DERPMap of a connection.
 func (c *Conn) SetDERPMap(derpMap *tailcfg.DERPMap) {
-	c.configMaps.setDERPMap(DERPMapToProto(derpMap))
+	c.configMaps.setDERPMap(derpMap)
 }
 
 func (c *Conn) SetDERPForceWebSockets(v bool) {