AK: Rename create<T> => make_ref_counted<T>

And also try_create<T> => try_make_ref_counted<T>.

A global "create" was a bit much. The new name matches make<T> better,
which we've used for making single-owner objects since forever.

Userland/Applications/PixelPaint/Guide.h

@@ -27,7 +27,7 @@ public:
 
     static NonnullRefPtr<Guide> construct(Orientation orientation, float offset)
     {
-        return create<Guide>(orientation, offset);
+        return make_ref_counted<Guide>(orientation, offset);
     };
 
     Orientation orientation() const { return m_orientation; }