Refactor bastardkb/charybdis/3x5 (#25488)

* Refactor bastardkb/charybdis/3x5

- Migrate various configuration to data-driven
- Use short SPDX license headers
- Remove configuration that trends towards user-specific (CRC Table)
- Migrate common configuration upwards
- Migrate keymap to JSON
- Remove likely unneeded v1 revision per #23638
- Remove revisions splinky_2, splinky_3, and stemcell where a converter
  should be used
- Rename v2/elitec -> elitec. Specifically named elitec, as this board
  requires pin compatibility with an Elite-C (bottom 5 pins)

* Aliases

data/mappings/keyboard_aliases.hjson

@@ -68,6 +68,18 @@
     "bakeneko80": {
         "target": "kkatano/bakeneko80"
     },
+    "bastardkb/charybdis/3x5/v2/elitec": {
+        "target": "bastardkb/charybdis/3x5/elitec"
+    },
+    "bastardkb/charybdis/3x5/v2/splinky_2": {
+        "target": "bastardkb/charybdis/3x5/elitec"
+    },
+    "bastardkb/charybdis/3x5/v2/splinky_3": {
+        "target": "bastardkb/charybdis/3x5/elitec"
+    },
+    "bastardkb/charybdis/3x5/v2/stemcell": {
+        "target": "bastardkb/charybdis/3x5/elitec"
+    },
     "bastardkb/dilemma/3x5_2/splinky": {
         "target": "bastardkb/dilemma/3x5_2/promicro"
     },