[Keyboard] Add Binepad BNK8 keyboard (#24598)

* Add Binepad BNK8 keyboard

* Moved keymap.c to keymap.json

* Fix product page URL

* RGB_ -> RM_ keycodes after this round of breaking changes

Co-authored-by: Ryan <fauxpark@gmail.com>

---------

Co-authored-by: Ryan <fauxpark@gmail.com>

keyboards/binepad/bnk8/readme.md

@@ -0,0 +1,26 @@
+# BINEPAD BNK8
+
+![BINEPAD BNK8](https://i.imgur.com/HFIZg48h.jpeg)
+
+A compact 8-key 3x3 macropad with a rotary encoder at the top right.
+
+* Keyboard Maintainer: [binepad](https://github.com/binepad)
+* Hardware Supported: BINPAD BNK8
+* Hardware Availability: [binepad.com](https://binepad.com/products/bnk8)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make binepad/bnk8:default
+
+Flashing example for this keyboard:
+
+    make binepad/bnk8:default:flash
+
+See the [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) and the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information. Brand new to QMK? Start with our [Complete Newbs Guide](https://docs.qmk.fm/#/newbs).
+
+## Bootloader
+
+Enter the bootloader in 2 ways:
+
+* **Bootmagic reset**: Hold down the key at (0,0) in the matrix (usually the top left key) and plug in the keyboard
+* **Keycode in layout**: Press the key mapped to `QK_BOOT` if it is available