Double-clicking in a `TextBox` with `PasswordChar` set selects all text when the password is not revealed. (#14973)

If the password text is revealed, the pre-existing word-based selection model remains (the closest word to the pointer position is selected.)

Related to https://github.com/AvaloniaUI/Avalonia/issues/14956

src/Avalonia.Controls/TextBox.cs

@@ -1578,6 +1578,13 @@ namespace Avalonia.Controls
 
                         break;
                     case 2:
+                        if (IsPasswordBox && !RevealPassword)
+                        {
+                            // double-clicking in a cloaked single-line password box selects all text
+                            // see https://github.com/AvaloniaUI/Avalonia/issues/14956
+                            goto case 3;
+                        }
+
                         if (!StringUtils.IsStartOfWord(text, caretIndex))
                         {
                             selectionStart = StringUtils.PreviousWord(text, caretIndex);