client/tailscale/apitype: move local API types to new apitype package

They were scattered/duplicated in misc places before.

It can't be in the client package itself for circular dep reasons.

This new package is basically tailcfg but for localhost
communications, instead of to control.

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

ipn/localapi/localapi.go

@@ -23,6 +23,7 @@ import (
 	"time"
 
 	"inet.af/netaddr"
+	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/ipn"
 	"tailscale.com/ipn/ipnlocal"
 	"tailscale.com/ipn/ipnstate"
@@ -143,7 +144,7 @@ func (h *Handler) serveWhoIs(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "no match for IP:port", 404)
 		return
 	}
-	res := &tailcfg.WhoIsResponse{
+	res := &apitype.WhoIsResponse{
 		Node:        n,
 		UserProfile: &u,
 	}
@@ -340,7 +341,7 @@ func (h *Handler) serveFilePut(w http.ResponseWriter, r *http.Request) {
 	}
 	stableID, filenameEscaped := tailcfg.StableNodeID(upath[:slash]), upath[slash+1:]
 
-	var ft *ipnlocal.FileTarget
+	var ft *apitype.FileTarget
 	for _, x := range fts {
 		if x.Node.StableID == stableID {
 			ft = x