LibJS+WebContent+Browser+js: Implement console.group() methods

This implements:
- console.group()
- console.groupCollapsed()
- console.groupEnd()

In the Browser, we use `<details>` for the groups, which is not actually
implemented yet, so groups are always open.

In the REPL, groups are non-interactive, but still indent any output.
This looks weird since the console prompt and return values remain on
the far left, but this matches what Node does so it's probably fine. :^)
I expect `console.group()` is not used much outside of browsers.

Userland/Libraries/LibJS/Runtime/ConsoleObject.h

@@ -29,6 +29,9 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(count_reset);
     JS_DECLARE_NATIVE_FUNCTION(clear);
     JS_DECLARE_NATIVE_FUNCTION(assert_);
+    JS_DECLARE_NATIVE_FUNCTION(group);
+    JS_DECLARE_NATIVE_FUNCTION(group_collapsed);
+    JS_DECLARE_NATIVE_FUNCTION(group_end);
 };
 
 }