feat: add knulli, amberelec and emuelec platforms

Each OS publishes Batocera's systems dict (knulli-systems, and
batocera-systems at AmberELEC's newest prerelease commit and EmuELEC v4.8),
read with the shared parser. Cores come from each OS's own ES list.
AmberELEC and EmuELEC declare neogeo/ and ports/ beside bios/ from
/storage/roms, so their packs extract there and core_destination puts
core files under bios/.

scripts/scraper/es_emulators.py

@@ -0,0 +1,88 @@
+"""The emulators an EmulationStation system list offers, by profile names.
+
+AmberELEC writes its list as es_systems.cfg XML, EmuELEC as an es_systems.json
+it turns into that XML at build time. Both name, per system, the emulators a
+user may pick and the cores under each. Some emulators are libretro front
+ends (RetroArch, retrorun) whose cores are libretro core names. Every other
+emulator is a standalone program named by the OS (`HATARISA`, `PPSSPPSDL`).
+"""
+
+from __future__ import annotations
+
+import json
+import re
+
+from safeparse import parse_untrusted_xml
+
+
+def xml_emulators(text: str) -> dict[str, set[str]]:
+    """Emulator -> cores, from an es_systems.cfg."""
+    root = parse_untrusted_xml(text, "es_systems.cfg")
+    pairs: dict[str, set[str]] = {}
+    for emulator in root.iter("emulator"):
+        name = emulator.get("name")
+        if name:
+            pairs.setdefault(name, set()).update(
+                core.text.strip() for core in emulator.iter("core") if core.text
+            )
+    if not pairs:
+        raise ValueError("es_systems.cfg names no emulator")
+    return pairs
+
+
+def json_emulators(text: str) -> dict[str, set[str]]:
+    """Emulator -> cores, from an es_systems.json."""
+    pairs: dict[str, set[str]] = {}
+    for system in json.loads(text).get("systems", []):
+        for emulator in system.get("emulators") or []:
+            pairs.setdefault(emulator["name"], set()).update(
+                core["name"] for core in emulator.get("cores") or []
+            )
+    if not pairs:
+        raise ValueError("es_systems.json names no emulator")
+    return pairs
+
+
+def standalone_names(emulator: str) -> list[str]:
+    """The names a profile may know a standalone emulator by.
+
+    The OS's own spelling, its lowercase, and the lowercase without the
+    `sa` suffix the ELEC family appends to a standalone build of an emulator
+    that also exists as a core (`HATARISA`, `scummvmsa`, `yabasanshiroSA`).
+    """
+    lower = emulator.lower()
+    names = [emulator, lower]
+    stripped = re.sub(r"-?sa$", "", lower)
+    if stripped:
+        names.append(stripped)
+    return list(dict.fromkeys(names))
+
+
+def es_cores(
+    pairs: dict[str, set[str]],
+    runners: dict[str, str | None],
+    renamed: dict[str, str] | None = None,
+) -> tuple[list[str], list[str], list[str]]:
+    """(cores, standalone_cores, dual_mode_cores) of an ES system list.
+
+    `runners` maps each emulator that runs libretro cores to None when the
+    cores it lists are libretro core names, or to the one core it always
+    loads (AmberELEC's `mame` lists MAME machines and loads the MAME core).
+    `renamed` gives the emulator a standalone name stands for when the
+    suffix rule cannot (`PPSSPPSDL` is PPSSPP), each one read in the OS's
+    launch code.
+    """
+    renamed = renamed or {}
+    libretro: set[str] = set()
+    for runner, fixed in runners.items():
+        if runner in pairs:
+            libretro.update([fixed] if fixed else pairs[runner])
+    standalone: set[str] = set()
+    for emulator in pairs:
+        if emulator in runners:
+            continue
+        standalone.update(standalone_names(emulator))
+        if emulator in renamed:
+            standalone.add(renamed[emulator])
+    dual = {name for name in standalone if name in libretro}
+    return sorted(libretro | standalone), sorted(standalone), sorted(dual)