Refactor BT compiler to support multiple code directories (#97240)

Changes the behavior tree compiler to take a list of code directories
instead of just using hard-coded `code/`, this makes it possible for
downstreams to have modular behavior trees properly compiled

Nearly all downstream forks active today have code in places other than
`code/`, this makes the BT compiler account for that

N/A

.github/workflows/check_bt_compiled.yml

@@ -3,8 +3,8 @@ name: Check BT Compiled JSON
 on:
   pull_request:
     paths:
-      - "code/**/*.bt.json"
-      - "code/_generated/behavior_trees/**"
+      - "**/*.bt.json"
+      - "build/behavior_trees/**"
       - "code/__DEFINES/**"
       - "tools/build_bt.py"