modify various packages to use libremesh.mk.
drop the package lua-argparse since it is available in openwrt feeds.
adapt packages to apk version schema.

lime-system: add apk option in 92_add-lime-repos

ci: update feeds scheme to build C++ packages for 3 lastest openwrt branches
      the new scheme make these packages available at
      https://github.com/libremesh/lime-feed
      referenced by apk in /etc/apk/repositories as
      @libremesh_arch_packages https://feed.libremesh.org/arch_packages/master/openwrt_main/x86_64/packages.adb

ci: disable sign packages in main openwrt branch
      not yet supported, there is an active pull
      Support sign apk feed openwrt/gh-action-sdk#46
      to install packages use "apk add --allow-untrusted lime-docs"

…also apk

…ate README.md

…ild: calculate DEST_DIR once

…ename openwrt_branch_path