ipn/localapi: move EditPrefs to localapi

Follow-up/revision to recent 53cfff109b which
added EditPrefs.

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

ipn/message.go

@@ -80,7 +80,6 @@ type Command struct {
 	Login                 *tailcfg.Oauth2Token
 	Logout                *NoArgs
 	SetPrefs              *SetPrefsArgs
-	EditPrefs             *MaskedPrefs
 	RequestEngineStatus   *NoArgs
 	RequestStatus         *NoArgs
 	FakeExpireAfter       *FakeExpireAfterArgs
@@ -204,9 +203,6 @@ func (bs *BackendServer) GotCommand(ctx context.Context, cmd *Command) error {
 	} else if c := cmd.SetPrefs; c != nil {
 		bs.b.SetPrefs(c.New)
 		return nil
-	} else if c := cmd.EditPrefs; c != nil {
-		bs.b.EditPrefs(c)
-		return nil
 	} else if c := cmd.FakeExpireAfter; c != nil {
 		bs.b.FakeExpireAfter(c.Duration)
 		return nil
@@ -307,10 +303,6 @@ func (bc *BackendClient) SetPrefs(new *Prefs) {
 	bc.send(Command{SetPrefs: &SetPrefsArgs{New: new}})
 }
 
-func (bc *BackendClient) EditPrefs(mp *MaskedPrefs) {
-	bc.send(Command{EditPrefs: mp})
-}
-
 func (bc *BackendClient) RequestEngineStatus() {
 	bc.send(Command{RequestEngineStatus: &NoArgs{}})
 }