Everywhere: Remove unnecessary headers 1/4

Arbitrarily split up to make git bisect easier.

These unnecessary #include's were found by combining an automated tool (which
determined likely candidates) and some brain power (which decided whether
the #include is also semantically superfluous).

My favorite #include:

    #include "Applications/Piano/Music.h" // You can't have too much music in life!

AK/Format.cpp

@@ -35,7 +35,6 @@
 #    include <Kernel/Thread.h>
 #else
 #    include <stdio.h>
-#    include <unistd.h>
 #endif
 
 namespace AK {

AK/JsonPath.cpp

@@ -24,7 +24,6 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonPath.h>
 #include <AK/JsonValue.h>

AK/JsonValue.cpp

@@ -29,7 +29,6 @@
 #include <AK/JsonObject.h>
 #include <AK/JsonParser.h>
 #include <AK/JsonValue.h>
-#include <AK/StringBuilder.h>
 
 namespace AK {
 

AK/MappedFile.cpp

@@ -28,7 +28,6 @@
 #include <AK/ScopeGuard.h>
 #include <AK/String.h>
 #include <fcntl.h>
-#include <stdio.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <unistd.h>

Userland/Applications/PixelPaint/BrushTool.cpp

@@ -34,7 +34,6 @@
 #include <LibGUI/Slider.h>
 #include <LibGfx/Color.h>
 #include <LibGfx/Rect.h>
-#include <utility>
 
 namespace PixelPaint {
 

Userland/Libraries/LibCpp/AST.h

@@ -26,7 +26,6 @@
 
 #pragma once
 
-#include "Applications/Piano/Music.h"
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/Optional.h>
 #include <AK/RefCounted.h>

Userland/Libraries/LibGfx/BMPWriter.cpp

@@ -27,7 +27,6 @@
 #include <AK/Vector.h>
 #include <LibGfx/BMPWriter.h>
 #include <LibGfx/Bitmap.h>
-#include <cstring>
 
 namespace Gfx {