Fix action numbers (/handle UI default theme update) (#15840)

Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Client/UserInterface/Controls/SlotControl.cs

@@ -232,6 +232,7 @@ namespace Content.Client.UserInterface.Controls
 
         protected override void OnThemeUpdated()
         {
+            base.OnThemeUpdated();
             StorageButton.TextureNormal = Theme.ResolveTexture(_storageTexturePath);
             ButtonRect.Texture = Theme.ResolveTexture(_buttonTexturePath);
             HighlightRect.Texture = Theme.ResolveTexture(_highlightTexturePath);

Content.Client/UserInterface/Systems/Actions/Controls/ActionButton.cs

@@ -158,6 +158,7 @@ public sealed class ActionButton : Control
 
     protected override void OnThemeUpdated()
     {
+        base.OnThemeUpdated();
         Button.Texture = Theme.ResolveTexture("SlotBackground");
         Label.FontColorOverride = Theme.ResolveColorOrSpecified("whiteText");
     }

Content.Client/UserInterface/Systems/Actions/Controls/ActionPageButtons.xaml

@@ -3,7 +3,7 @@
     xmlns:controls="clr-namespace:Content.Client.UserInterface.Systems.Actions.Controls">
     <BoxContainer Orientation="Horizontal">
         <Control HorizontalExpand="True" SizeFlagsStretchRatio="1"/>
-        <TextureButton TexturePath="/Textures/Interface/Nano/left_arrow.svg.192dpi.png"
+        <TextureButton TexturePath="left_arrow.svg.192dpi"
                        SizeFlagsStretchRatio="1"
                        Scale="0.5 0.5"
                        HorizontalAlignment="Center"
@@ -13,7 +13,7 @@
         <Control HorizontalExpand="True" SizeFlagsStretchRatio="2"/>
         <Label Text="1" SizeFlagsStretchRatio="1" Name="Label" Access="Public" />
         <Control HorizontalExpand="True" SizeFlagsStretchRatio="2"/>
-        <TextureButton TexturePath="/Textures/Interface/Nano/right_arrow.svg.192dpi.png"
+        <TextureButton TexturePath="right_arrow.svg.192dpi"
                        SizeFlagsStretchRatio="1"
                        Scale="0.5 0.5"
                        HorizontalAlignment="Center"