Added custom components + moved/rewrote some

To organize the project a bit, decided to add a new folder inside the
ui folder, to hold all custom components. ui/components/

Rewrote IconTextField

I wasn't happy with its functionality, so I rewrote it to
include the following:

- Left aligned centered icons
- Animated gif support (ex: loading wheels)
- Custom hover effects (color change)
- Input blocking

All changes:

- Created new folder ui/components/
- Moved JShadowLabel and JShadowLabelUI to components folder
- Moved IconTextField to components folder
- Rewrote IconTextField
- Created new components: MaterialTab & MaterialTabGroup
- Created new components: CustomScrollBarUI
- Created new components: PluginErrorPanel
- Created new components: ThinProgressBar
- Applied the new scroll bar ui to the UI defaults (UIManager)

runelite-client/src/main/java/net/runelite/client/util/SwingUtil.java

@@ -60,6 +60,7 @@ import static javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE;
 import javax.swing.plaf.FontUIResource;
 import lombok.extern.slf4j.Slf4j;
 import net.runelite.client.ui.NavigationButton;
+import net.runelite.client.ui.components.CustomScrollBarUI;
 import org.pushingpixels.substance.internal.SubstanceSynapse;
 import org.pushingpixels.substance.internal.utils.SubstanceCoreUtilities;
 
@@ -82,6 +83,7 @@ public class SwingUtil
 
 		UIManager.put("Button.foreground", Color.WHITE);
 		UIManager.put("MenuItem.foreground", Color.WHITE);
+		UIManager.put("ScrollBarUI", CustomScrollBarUI.class.getName());
 
 		// Do not render shadows under popups/tooltips.
 		// Fixes black boxes under popups that are above the game applet.