AK: Add a forward declaration header

You can now #include <AK/Forward.h> to get most of the AK types as
forward declarations.

Header dependency explosion is one of the main contributors to compile
times at the moment, so this is a step towards smaller include graphs.

Libraries/LibELF/ELFDynamicLoader.h

@@ -26,14 +26,14 @@
 
 #pragma once
 
-#include <LibELF/ELFDynamicObject.h>
-#include <LibELF/ELFImage.h>
-#include <LibELF/exec_elf.h>
-#include <mman.h>
-
+#include <AK/Assertions.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/String.h>
+#include <LibELF/ELFDynamicObject.h>
+#include <LibELF/ELFImage.h>
+#include <LibELF/exec_elf.h>
+#include <sys/mman.h>
 
 #define ALIGN_ROUND_UP(x, align) ((((size_t)(x)) + align - 1) & (~(align - 1)))
 

Libraries/LibELF/ELFDynamicObject.cpp

@@ -24,12 +24,10 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <AK/String.h>
+#include <AK/StringBuilder.h>
 #include <LibELF/ELFDynamicObject.h>
 #include <LibELF/exec_elf.h>
-
-#include <AK/StringBuilder.h>
-
-#include <assert.h>
 #include <stdio.h>
 
 static const char* name_for_dtag(Elf32_Sword d_tag);

Libraries/LibELF/ELFDynamicObject.h

@@ -26,6 +26,7 @@
 
 #pragma once
 
+#include <AK/Assertions.h>
 #include <LibBareMetal/Memory/VirtualAddress.h>
 #include <LibELF/exec_elf.h>