Add test for bug #78075, json detection

Author: weltling

ext/fileinfo/tests/finfo_file_002.phpt

@@ -29,6 +29,8 @@ array(%d) {
   string(9) "image/gif"
   ["%s/resources/test.jpg"]=>
   string(10) "image/jpeg"
+  ["%s/test.json"]=>
+  string(16) "application/json"
   ["%s/resources/test.mp3"]=>
   string(10) "audio/mpeg"
   ["%s/resources/test.pdf"]=>

ext/fileinfo/tests/resources/test.json

@@ -0,0 +1,13 @@
+{
+    "abc": "edf",
+    "json": "crab",
+    "ololo": [
+        1,
+        2,
+        3
+    ],
+    "subcrab": {
+        "name": "crab",
+        "surname": "subcrab"
+    }
+}