Rename jerry-port.h to jerryscript-port.h (#1762)

All public headers should follow the pattern `jerryscript[-*].h`.
The `jerry-api.h` to `jerryscript.h` renaming has already happened
a while ago, now it's time for the port API header to follow.

This patch
* renames the public header file,
* updates all includes to use the new file name (in `jerry-main`,
  in all the targets, and in the docs), and
* keeps `jerry-port.h` as a deprecated forwarding header to leave
  some time for external users to follow up with this change.

As a related change, the header of the default port implementation
is also changed to `jerryscript-port-default.h`.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

docs/03.API-EXAMPLE.md

@@ -177,7 +177,7 @@ The following example function will output a JavaScript value:
 #include <string.h>
 
 #include "jerryscript.h"
-#include "jerry-port.h"
+#include "jerryscript-port.h"
 
 static void
 print_value (const jerry_value_t value)
@@ -247,7 +247,7 @@ Shell operation can be described with the following loop:
 #include <string.h>
 
 #include "jerryscript.h"
-#include "jerry-port.h"
+#include "jerryscript-port.h"
 
 static void print_value (const jerry_value_t);