Fix clearTextureAtlas call as implemented on IRenderer

This is the root cause of microsoft/vscode#162996

addons/xterm-addon-webgl/src/WebglAddon.ts

@@ -60,6 +60,6 @@ export class WebglAddon implements ITerminalAddon {
   }
 
   public clearTextureAtlas(): void {
-    this._renderer?.clearCharAtlas();
+    this._renderer?.clearTextureAtlas();
   }
 }

addons/xterm-addon-webgl/src/WebglRenderer.ts

@@ -295,7 +295,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
     }
   }
 
-  public clearCharAtlas(): void {
+  public clearTextureAtlas(): void {
     this._charAtlas?.clearTexture();
     this._clearModel(true);
     this._updateModel(0, this._terminal.rows - 1);