Keyboard: Add support for Diverge TM2 (#3829)

* pulling in diverge tm2 from staging branch

* cleaned up comments, docs, licenses

* refactored apparent grid to make 2u spacebars more obvious

* various delinting from noroadsleft review

* most of drashna's feedback responded to

- lots of lint swept
- used more modern tri-layer functions
- still need to adopt modern split support.

* switch to common split code. remove comment cruft

* tapping force hold makes LT way more usable for rapid ,  sequences

keyboards/divergetm2/keymaps/xtonhasvim/config.h

@@ -0,0 +1,23 @@
+#pragma once
+
+// help for fast typist+dual function keys?
+#define PERMISSIVE_HOLD
+// Let me type `ls -l` more quickly.
+#define TAPPING_FORCE_HOLD
+
+// where is the cord plugged in?
+#define MASTER_RIGHT
+
+/* speed up mousekeys a bit */
+#define MOUSEKEY_DELAY             50
+#define MOUSEKEY_INTERVAL          20
+#define MOUSEKEY_MAX_SPEED         8
+#define MOUSEKEY_TIME_TO_MAX       30
+#define MOUSEKEY_WHEEL_MAX_SPEED   8
+#define MOUSEKEY_WHEEL_TIME_TO_MAX 40
+
+// because I'm lazy and didn't case out the rgb support
+#define RGBLED_NUM 2
+
+#define BACKLIGHT_PIN B7
+#define BACKLIGHT_LEVELS 3