fix: games tools write whole files, name options

The games importers wrote through fixed .part names, the new options had
no help text, and romfolders stopped on the first setup the offline cache
lacked. RetroArch's rom folder map is regenerated from its source spec
(path null, as the schema says). The installer's Python 3.8 job imports
the games tests without pyyaml, so the region rules load lazily.

scripts/scraper/arcade_parent_importer.py

@@ -49,6 +49,7 @@ from collections.abc import Callable, Iterator
 from dataclasses import dataclass, field
 from pathlib import Path
 
+from ..artifacts import write_text_atomic
 from ..common import load_emulator_profiles
 from .romset_dat_importer import (
     LISTXML_CHUNK,
@@ -1117,21 +1118,24 @@ def write_if_changed(path: Path, text: str) -> bool:
     if path.is_file() and path.read_text(encoding="utf-8") == text:
         return False
     path.parent.mkdir(parents=True, exist_ok=True)
-    scratch = path.with_suffix(path.suffix + ".part")
-    scratch.write_text(text, encoding="utf-8")
-    scratch.replace(path)
+    write_text_atomic(str(path), text)
     return True
 
 
 def main() -> int:
     parser = argparse.ArgumentParser(allow_abbrev=False, description=__doc__.splitlines()[0])
     which = parser.add_mutually_exclusive_group(required=True)
-    which.add_argument("--profile", action="append", choices=sorted(PROFILES))
-    which.add_argument("--all", action="store_true")
-    parser.add_argument("--emulators-dir", default="emulators")
-    parser.add_argument("--database", default="database.json")
-    parser.add_argument("--output-dir", type=Path, default=DEFAULT_OUTPUT)
-    parser.add_argument("--cache-dir", type=Path, default=DEFAULT_CACHE)
+    which.add_argument("--profile", action="append", choices=sorted(PROFILES),
+                       help="profile to import (repeatable)")
+    which.add_argument("--all", action="store_true", help="every profile with an arcade source")
+    parser.add_argument("--emulators-dir", default="emulators",
+                        help="profiles whose BIOS sets are read (default emulators)")
+    parser.add_argument("--database", default="database.json",
+                        help="collection index, to name BIOS sets the collection lacks")
+    parser.add_argument("--output-dir", type=Path, default=DEFAULT_OUTPUT,
+                        help=f"where the parent maps are written (default {DEFAULT_OUTPUT})")
+    parser.add_argument("--cache-dir", type=Path, default=DEFAULT_CACHE,
+                        help=f"downloaded DATs and sources (default {DEFAULT_CACHE})")
     parser.add_argument("--offline", action="store_true", help="read the download cache only")
     parser.add_argument("--dry-run", action="store_true", help="print coverage, write nothing")
     args = parser.parse_args()