Fix TextBox MaxLines property not constraining height in Semi theme (#753)

* Initial plan

* Fix TextBox MaxLines property by adding Name=PART_ScrollViewer to ScrollViewer elements

Co-authored-by: gehongyan <21241496+gehongyan@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

src/Semi.Avalonia/Controls/TextBox.axaml

@@ -59,6 +59,7 @@
                                 Foreground="{DynamicResource TextBoxInnerForeground}"
                                 IsVisible="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=InnerLeftContent, Converter={x:Static ObjectConverters.IsNotNull}}" />
                             <ScrollViewer
+                                Name="PART_ScrollViewer"
                                 Grid.Column="1"
                                 AllowAutoHide="{TemplateBinding (ScrollViewer.AllowAutoHide)}"
                                 HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
@@ -292,6 +293,7 @@
                                 Foreground="{DynamicResource TextBoxInnerForeground}"
                                 IsVisible="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=InnerLeftContent, Converter={x:Static ObjectConverters.IsNotNull}}" />
                             <ScrollViewer
+                                Name="PART_ScrollViewer"
                                 Grid.Column="1"
                                 AllowAutoHide="{TemplateBinding (ScrollViewer.AllowAutoHide)}"
                                 HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"
@@ -512,6 +514,7 @@
                             Foreground="{DynamicResource TextBoxInnerForeground}"
                             IsVisible="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=InnerLeftContent, Converter={x:Static ObjectConverters.IsNotNull}}" />
                         <ScrollViewer
+                            Name="PART_ScrollViewer"
                             Grid.Column="1"
                             AllowAutoHide="{TemplateBinding (ScrollViewer.AllowAutoHide)}"
                             HorizontalScrollBarVisibility="{TemplateBinding (ScrollViewer.HorizontalScrollBarVisibility)}"