[cmake] CPMUtil rewrite of the day number 852 (#4130)

Composite PR for several changes to CPMUtil, most notably:
- https://git.crueter.xyz/CMake/CPMUtil/pulls/19
- https://git.crueter.xyz/CMake/CPMUtil/pulls/22
- https://git.crueter.xyz/CMake/CPMUtil/pulls/24
- https://git.crueter.xyz/CMake/CPMUtil/pulls/25

These contain a lot of changes that generally simplify control flow and improve ease-of-use. Read those descriptions and patchsets for more info.

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4130
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>

tools/cpm/cmake/package/add.cmake

@@ -0,0 +1,104 @@
+#!/usr/bin/env -S cmake -P
+
+# SPDX-FileCopyrightText: Copyright 2026 crueter
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+cmake_minimum_required(VERSION 3.31)
+
+include(${CMAKE_CURRENT_LIST_DIR}/../ScriptUtils.cmake)
+
+function(usage)
+    echo([=[
+Usage: add.cmake [OPTIONS...]
+
+Internal use only.
+]=])
+endfunction()
+
+if (NOT DEFINED KEY)
+    fatal("KEY is required")
+endif()
+
+if (NOT DEFINED REPO)
+    fatal("REPO is required")
+endif()
+
+if (NOT DEFINED VERSION)
+    fatal("VERSION is required")
+endif()
+
+
+if (NOT DEFINED CI)
+    set(CI FALSE)
+endif()
+
+# construct json
+set(object "{}")
+
+macro(add key val)
+    set(${key} ${val})
+    string(JSON object SET ${object} ${key} "\"${val}\"")
+endmacro()
+
+add(repo ${REPO})
+add(version ${VERSION})
+
+if (DEFINED GIT_HOST AND NOT "${GIT_HOST}" STREQUAL github.com)
+    add(git_host ${GIT_HOST})
+else()
+    set(git_host github.com)
+endif()
+
+if (DEFINED PACKAGE)
+    add(package ${PACKAGE})
+else()
+    set(package ${KEY})
+endif()
+
+if (DEFINED FIND_ARGS)
+    add(find_args "${FIND_ARGS}")
+endif()
+
+if (DEFINED MIN_VERSION)
+    add(min_version ${MIN_VERSION})
+endif()
+
+if (DEFINED ARTIFACT)
+    add(artifact ${ARTIFACT})
+endif()
+
+if (CI)
+    add(ci true)
+
+    if (DEFINED DISABLED_PLATFORMS)
+        list_to_array(${DISABLED_PLATFORMS} json_disabled)
+        string(JSON object SET "${object}" disabled_platforms "${json_disabled}")
+    endif()
+else()
+    if (DEFINED OPTIONS)
+        list_to_array(${OPTIONS} json_options)
+        string(JSON object SET "${object}" options "${json_options}")
+    endif()
+
+    # get hash
+    get_package_url_object(pkg_url)
+    get_package_hash("${pkg_url}" pkg_hash)
+
+    add(hash ${pkg_hash})
+
+endif()
+
+echo("\"${KEY}\": ${object}")
+
+# now write
+get_cpmfile_content(cpmfile)
+
+# update cached cpmfile content
+string(JSON cpmfile SET "${cpmfile}" "${KEY}" "${object}")
+
+# write cached cpmfile
+get_cpmfile_path(file)
+file(WRITE ${file} "${cpmfile}")
+format_cpmfile()
+
+echo("-- Added ${KEY}")