[cmake, docs, tools] update CPMUtil (#3183)

Rewrote the entire tooling scheme. That's about it, just make sure
tooling works as expected everywhere.

Signed-off-by: crueter <crueter@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3183
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: Lizzie <lizzie@eden-emu.dev>

tools/cpm/package/which.sh

@@ -0,0 +1,12 @@
+#!/bin/sh -e
+
+# SPDX-FileCopyrightText: Copyright 2025 crueter
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+# check which file a package is in
+
+JSON=$(echo "$CPMFILES" | xargs grep -l "\"$1\"")
+
+[ -z "$JSON" ] && echo "!! No cpmfile definition for $1" >&2 && exit 1
+
+echo "$JSON"