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.

coderd/workspaceagents.go

@@ -904,7 +904,7 @@ func (api *API) _dialWorkspaceAgentTailnet(agentID uuid.UUID) (*codersdk.Workspa
 				}
 
 				derpMap := api.DERPMap()
-				if lastDERPMap == nil || tailnet.CompareDERPMaps(lastDERPMap, derpMap) {
+				if lastDERPMap == nil || !tailnet.CompareDERPMaps(lastDERPMap, derpMap) {
 					conn.SetDERPMap(derpMap)
 					lastDERPMap = derpMap
 				}