[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/rm.sh

@@ -0,0 +1,30 @@
+#!/bin/sh -e
+
+# SPDX-FileCopyrightText: Copyright 2025 crueter
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+RETURN=0
+
+usage() {
+	cat <<EOF
+Usage: cpmutil.sh package rm [PACKAGE]...
+
+Delete a package or packages' cpmfile definition(s).
+
+EOF
+
+	exit $RETURN
+}
+
+[ $# -lt 1 ] && usage
+
+for pkg in "$@"; do
+	JSON=$("$SCRIPTS"/which.sh "$pkg") || {
+		echo "!! No cpmfile definition for $pkg"
+		continue
+	}
+
+	jq --indent 4 "del(.\"$pkg\")" "$JSON" >"$JSON".tmp
+	mv "$JSON".tmp "$JSON"
+	echo "-- Removed $pkg from $JSON" || :
+done