packages should have "PKGARCH=all" set

currently there is no binary in any of the packages, so they can safely be set to PKGARCH=all.
For this we rely on the luci.mk if the luci-feed which defines ```LUCI_PKGARCH?=$(if $(realpath src/Makefile),,all)``` (https://github.com/openwrt/luci/blob/c351beea561acafa088a3fd3d82bfec93ee45cd4/luci.mk#L12) for some reason this seems no to be evaluated correctly. So we end up in having ARCH-specifiy packages without any need.

Start by reading the referenced luci.mk definition of LUCI_PKGARCH and its src/Makefile condition, then inspect the package definitions in this repository to see how the value is evaluated. Done means packages without binaries are emitted with PKGARCH=all rather than architecture-specific metadata, with the resulting package metadata verified.

Written by the indexing model from the issue text.