Indicate when caps lock is on while reading password

tools/tui/loop/key-encoding.go

@@ -93,6 +93,10 @@ func (self KeyModifiers) String() string {
 	return strings.Join(ans, "+")
 }
 
+func (self KeyModifiers) HasCapsLock() bool {
+	return self&CAPS_LOCK != 0
+}
+
 type KeyEvent struct {
 	Type         KeyEventType
 	Mods         KeyModifiers
@@ -121,6 +125,10 @@ func (self *KeyEvent) String() string {
 	return ans + "}"
 }
 
+func (self *KeyEvent) HasCapsLock() bool {
+	return self.Mods.HasCapsLock()
+}
+
 func KeyEventFromCSI(csi string) *KeyEvent {
 	if len(csi) == 0 {
 		return nil