Refactor helix/rev2 (#25429)

* Refactor helix/rev2

- Rename rev2 -> beta & update keyboard aliases accordingly
- Removes redundant back, base, sc, under, & qmk_conf revisions
- Removes unnecessary keymaps
- Migrates legacy defines and configuration to keyboard.json
- Tidy's keymap and migrates to JSON
- Fixes RGB configuration to illuminate 32 LEDs per half
- Adds an alternate 4 row layout for snappable PCB
- Tidy's up OLED code
- Enables standard features (bootmagic, extrakey, etc.)

data/mappings/keyboard_aliases.hjson

@@ -269,38 +269,11 @@
     "handwired/jscotto/scottostarter": {
         "target": "handwired/scottokeebs/scottostarter"
     },
-    "helix/rev2/back/oled": {
-        "target": "helix/rev2/back"
+    "helix": {
+        "target": "helix/beta"
     },
-    "helix/rev2/oled": {
-        "target": "helix/rev2"
-    },
-    "helix/rev2/oled/back": {
-        "target": "helix/rev2/back"
-    },
-    "helix/rev2/oled/under": {
-        "target": "helix/rev2/under"
-    },
-    "helix/rev2/sc/back": {
-        "target": "helix/rev2/sc"
-    },
-    "helix/rev2/sc/oled": {
-        "target": "helix/rev2/sc"
-    },
-    "helix/rev2/sc/oledback": {
-        "target": "helix/rev2/sc"
-    },
-    "helix/rev2/sc/oledunder": {
-        "target": "helix/rev2/sc"
-    },
-    "helix/rev2/sc/under": {
-        "target": "helix/rev2/sc"
-    },
-    "helix/rev2/under": {
-        "target": "helix/rev2/sc"
-    },
-    "helix/rev2/under/oled": {
-        "target": "helix/rev2/under"
+    "helix/rev2": {
+        "target": "helix/beta"
     },
     "honeycomb": {
         "target": "keyhive/honeycomb"
@@ -2290,12 +2263,6 @@
     "handwired/dygma/raise": {
         "target": "handwired/dygma/raise/ansi"
     },
-    "helix": {
-        "target": "helix/rev2/base"
-    },
-    "helix/rev2": {
-        "target": "helix/rev2/base"
-    },
     "ibm/model_m/mschwingen": {
         "target": "ibm/model_m/mschwingen/led_wired"
     },