feat: place files outside the bios tree

A platform that binds part of a standalone layout leaves the entries no
binding covers in a folder outside the BIOS tree: they are no longer
packed at the BIOS root, and the manifest names them (root: emulator,
outside_bios_folder). A launcher that executes a profile's file binds
the program folder: in the BIOS tree, below the roms directory a registry
entry names (root: roms, installed into the folder holding the BIOS
folder), or nowhere a pack reaches. A moved entry resolves by its own
path as well as by its destination.

uae4all gains kick.rom and rom.key in its working directory and loses a
not_bundled_on that named Recalbox, which runs uae4all-rpi. lexaloffle
declares that its programs read beside their executable, lists the
Windows build RetroBat runs and the pico8_dyn ROCKNIX runs on x86_64.

scripts/cross_reference.py

@@ -856,7 +856,7 @@ def _cross_reference_profile(
         # archive.
         # A platform declares files of its BIOS tree: none answers for one
         # the core reads below the save directory.
-        in_platform = not save_root and declaration_settles(
+        in_platform = not save_root and f.get("root") != "roms" and declaration_settles(
             f, fname, platform_names, effective_path, index.get("folded_slots", frozenset())
         )
 
@@ -941,6 +941,10 @@ def _cross_reference_profile(
         }
         if save_root:
             entry["root"] = "save"
+        elif f.get("unplaced"):
+            entry["unplaced"] = f["unplaced"]
+        elif f.get("root") == "roms":
+            entry["root"] = "roms"
         elif index.get("launcher_candidates") is not None:
             # What verify hands the launcher layer for the same entry.
             probe = {