[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/migrate.sh

@@ -0,0 +1,47 @@
+#!/bin/sh -e
+
+# SPDX-FileCopyrightText: Copyright 2025 crueter
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+SUBMODULES="$(git submodule status --recursive | cut -c2-)"
+
+[ -z "$SUBMODULES" ] && echo "No submodules defined!" && exit 0
+
+tmp=$(mktemp)
+printf '{}' >"$tmp"
+
+IFS="
+"
+for i in $SUBMODULES; do
+	sha=$(echo "$i" | cut -d" " -f1 | cut -c1-10)
+	ver=$(echo "$i" | cut -d" " -f3 | tr -d '()')
+
+	path=$(echo "$i" | cut -d" " -f2)
+	name=$(echo "$path" | awk -F/ '{print $NF}')
+
+	remote=$(git -C "$path" remote get-url origin)
+
+	host=$(echo "$remote" | cut -d"/" -f3)
+	[ "$host" = github.com ] && host=
+
+	repo=$(echo "$remote" | cut -d"/" -f4-5 | cut -d'.' -f1)
+
+	entry=$(jq -n --arg name "$name" \
+		--arg sha "$sha" \
+		--arg ver "$ver" \
+		--arg repo "$repo" \
+		--arg host "$host" \
+		'{
+        ($name): {
+            sha: $sha,
+            git_version: $ver,
+            repo: $repo
+        } + (if $host != "" then {git_host: $host} else {} end)
+        }')
+
+	jq --argjson new "$entry" '. + $new' "$tmp" >"${tmp}.new"
+	mv "$tmp.new" "$tmp"
+done
+
+jq '.' "$tmp" >cpmfile.json
+rm -f "$tmp"