Make FileAccess and DirAccess classes reference counted.

modules/mono/utils/string_utils.cpp

@@ -167,15 +167,13 @@ String escape_csharp_keyword(const String &p_name) {
 Error read_all_file_utf8(const String &p_path, String &r_content) {
 	Vector<uint8_t> sourcef;
 	Error err;
-	FileAccess *f = FileAccess::open(p_path, FileAccess::READ, &err);
+	Ref<FileAccess> f = FileAccess::open(p_path, FileAccess::READ, &err);
 	ERR_FAIL_COND_V_MSG(err != OK, err, "Cannot open file '" + p_path + "'.");
 
 	uint64_t len = f->get_length();
 	sourcef.resize(len + 1);
 	uint8_t *w = sourcef.ptrw();
 	uint64_t r = f->get_buffer(w, len);
-	f->close();
-	memdelete(f);
 	ERR_FAIL_COND_V(r != len, ERR_CANT_OPEN);
 	w[len] = 0;