[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>

CMakeModules/Findzstd.cmake

@@ -13,9 +13,12 @@ find_package_handle_standard_args(zstd
 if (zstd_FOUND AND NOT TARGET zstd::zstd)
     if (TARGET zstd::libzstd_shared)
         add_library(zstd::zstd ALIAS zstd::libzstd_shared)
+        add_library(zstd::libzstd ALIAS zstd::libzstd_shared)
     elseif (TARGET zstd::libzstd_static)
         add_library(zstd::zstd ALIAS zstd::libzstd_static)
+        add_library(zstd::libzstd ALIAS zstd::libzstd_static)
     else()
         add_library(zstd::zstd ALIAS PkgConfig::ZSTD)
+        add_library(zstd::libzstd ALIAS PkgConfig::ZSTD)
     endif()
 endif()