[tools, cmake] refactor: update/hash check scripts, use tags for some more deps, proper CPMUtil separation (#2666)

Uses tags for a bunch of deps that can use them

Also adds a bunmch of scripts to tools/cpm, notably for checking hashes
and checking for updates.

TODO for the future:
- CI target to check hashes
- Weekly CI to check for updates

Need to get that other CI runner up

additional stuff

- Ports gentoo fixes
- makes solaris work (TODO: sdl2)
- way better docs
- properly separates CPMUtil as a standalone project

Reviewed-on: #2666
Reviewed-by: Lizzie <lizzie@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

tools/cpm/fetch.sh

@@ -0,0 +1,36 @@
+#!/bin/sh -e
+
+# SPDX-FileCopyrightText: 2025 crueter
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+[ -z "$CPM_SOURCE_CACHE" ] && CPM_SOURCE_CACHE=$PWD/.cache/cpm
+
+mkdir -p "$CPM_SOURCE_CACHE"
+
+# shellcheck disable=SC1091
+. tools/cpm/common.sh
+
+# shellcheck disable=SC1091
+. tools/cpm/download.sh
+
+# shellcheck disable=SC2034
+ROOTDIR="$PWD"
+
+TMP=$(mktemp -d)
+
+# shellcheck disable=SC2034
+for PACKAGE in "$@"
+do
+	export PACKAGE
+	# shellcheck disable=SC1091
+	. tools/cpm/package.sh
+
+    if [ "$CI" = "true" ]; then
+        ci_package
+	else
+		echo "-- Downloading regular package $PACKAGE, with key $KEY, from $DOWNLOAD"
+	    download_package
+    fi
+done
+
+rm -rf "$TMP"