[Keyboard] Monstargear XO87 Solderable support (#11716)

* Support for XO87 solderable version

* cleanup

* Remove abandoned code

* replaced KEYMAP with LAYOUT and moved LAYOUT macro to solderable.h.  deleted unneeded files.

* Update keyboards/monstargear/xo87/solderable/keymaps/via/keymap.c

* update info.json with missing keys

* Apply suggestions from code review

* Apply suggestions from code review

correct layout macro

keyboards/monstargear/xo87/solderable/keymaps/via/config.h

@@ -0,0 +1,18 @@
+/* Copyright 2021 datafx
+ *
+ * This program 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, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#define VIA_QMK_RGBLIGHT_ENABLE