feat: Add Radiomaster Boxer (#2877)

* Radiomaster Boxer

* chore: Add Build system bits

* chore: `EEPROM_VARIANT` no longer used

.github/workflows/actions.yml

@@ -97,7 +97,7 @@ jobs:
           - t18
           - t8;zorro;commando8
           - tlite;tpro;lr3pro
-          - tx12;tx12mk2
+          - tx12;tx12mk2;boxer
           - tx16s
           - x10;x10-access
           - x12s

.github/workflows/nightly.yml

@@ -24,7 +24,7 @@ jobs:
           - t18
           - t8;zorro;commando8
           - tlite;tpro;lr3pro
-          - tx12;tx12mk2
+          - tx12;tx12mk2;boxer
           - tx16s
           - x10;x10-access
           - x12s