SSH connection status indicators

- Add Connected bool field to vfs.Entry and RemoteMount
- Track connection status in sshState.connectedHosts
- Show status icon (connected/disconnected) in pane header when browsing remote host
- Async SSH connection test with cancel support for Add Host dialog
- Colored labels and styled help text in SSH dialogs
- Confirmation dialog when deleting manually-added SSH hosts

vendor/golang.org/x/sys/windows/syscall_windows.go

@@ -900,6 +900,7 @@ const socket_error = uintptr(^uint32(0))
 //sys   NotifyRouteChange2(family uint16, callback uintptr, callerContext unsafe.Pointer, initialNotification bool, notificationHandle *Handle) (errcode error) = iphlpapi.NotifyRouteChange2
 //sys   NotifyUnicastIpAddressChange(family uint16, callback uintptr, callerContext unsafe.Pointer, initialNotification bool, notificationHandle *Handle) (errcode error) = iphlpapi.NotifyUnicastIpAddressChange
 //sys   CancelMibChangeNotify2(notificationHandle Handle) (errcode error) = iphlpapi.CancelMibChangeNotify2
+//sys	IsProcessorFeaturePresent(ProcessorFeature uint32) (ret bool) = kernel32.IsProcessorFeaturePresent
 
 // For testing: clients can set this flag to force
 // creation of IPv6 sockets to return EAFNOSUPPORT.
@@ -1489,20 +1490,6 @@ func Getgid() (gid int)                  { return -1 }
 func Getegid() (egid int)                { return -1 }
 func Getgroups() (gids []int, err error) { return nil, syscall.EWINDOWS }
 
-type Signal int
-
-func (s Signal) Signal() {}
-
-func (s Signal) String() string {
-	if 0 <= s && int(s) < len(signals) {
-		str := signals[s]
-		if str != "" {
-			return str
-		}
-	}
-	return "signal " + itoa(int(s))
-}
-
 func LoadCreateSymbolicLink() error {
 	return procCreateSymbolicLinkW.Find()
 }