fullbuild: Call script/bootstrap before clone (#383)

fullbuild would previously fail if the parent repository hadn't
initialized submodules yet, due to the use of --reference

Fixes #382

script/fullbuild

@@ -62,6 +62,8 @@ main() {
     local bootloader_commit="$1"
     local firmware_commit="$2"
 
+    script/bootstrap
+
     worktree_setup "$BOOTLOADER_DIR" "$bootloader_commit"
     worktree_build "$BOOTLOADER_DIR"