Style: Harmonize header includes in platform ports

This applies our existing style guide, and adds a new rule to that style
guide for modular components such as platform ports and modules:

Includes from the platform port or module should be included with relative
paths (relative to the root folder of the modular component, e.g.
`platform/linuxbsd/`), in their own section before Godot's "core" includes.

The `api` and `export` subfolders also need to be handled as self-contained
(and thus use relative paths for their "local" includes) as they are all
compiled for each editor platform, without necessarily having the api/export
matching platform folder in the include path.
E.g. the Linux editor build will compile `platform/android/{api,export}/*.cpp`
and those need to use relative includes for it to work.

platform/android/java_godot_view_wrapper.h

@@ -31,12 +31,13 @@
 #ifndef JAVA_GODOT_VIEW_WRAPPER_H
 #define JAVA_GODOT_VIEW_WRAPPER_H
 
+#include "string_android.h"
+
 #include "core/math/vector2.h"
+
 #include <android/log.h>
 #include <jni.h>
 
-#include "string_android.h"
-
 // Class that makes functions in java/src/org/godotengine/godot/GodotView.java callable from C++
 class GodotJavaViewWrapper {
 private: