Add: [Script] Basic information about loaded NewGRFs for scripts. (#9464)

Currently, scripts use various heuristics to detect loaded NewGRFs that are inherently unreliable.
The list of loaded NewGRFs is easily accessible to a human player, and thus giving
scripts the same information is consistent with the current approach to not give scripts
more information than a human player.

src/script/api/script_newgrf.cpp

@@ -0,0 +1,58 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file script_newgrf.cpp Implementation of ScriptNewGRF and friends. */
+
+#include "../../stdafx.h"
+#include "script_newgrf.hpp"
+#include "../../core/bitmath_func.hpp"
+#include "../../newgrf_config.h"
+#include "../../string_func.h"
+
+#include "../../safeguards.h"
+
+ScriptNewGRFList::ScriptNewGRFList()
+{
+	for (auto c = _grfconfig; c != nullptr; c = c->next) {
+		if (!HasBit(c->flags, GCF_STATIC)) {
+			this->AddItem(c->ident.grfid);
+		}
+	}
+}
+
+/* static */ bool ScriptNewGRF::IsLoaded(uint32 grfid)
+{
+	for (auto c = _grfconfig; c != nullptr; c = c->next) {
+		if (!HasBit(c->flags, GCF_STATIC) && c->ident.grfid == grfid) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+/* static */ uint32 ScriptNewGRF::GetVersion(uint32 grfid)
+{
+	for (auto c = _grfconfig; c != nullptr; c = c->next) {
+		if (!HasBit(c->flags, GCF_STATIC) && c->ident.grfid == grfid) {
+			return c->version;
+		}
+	}
+
+	return 0;
+}
+
+/* static */ char *ScriptNewGRF::GetName(uint32 grfid)
+{
+	for (auto c = _grfconfig; c != nullptr; c = c->next) {
+		if (!HasBit(c->flags, GCF_STATIC) && c->ident.grfid == grfid) {
+			return ::stredup(c->GetName());
+		}
+	}
+
+	return nullptr;
+}