WIP: pmb.chroot.apk: Install less packages explicitly in world

In my quick tests this seems to function the same as before this change.

Old behavior:

• pmbootstrap builds the full dependency tree for the rootfs
• if one of those packages exists in the locally built repository then those get used as a path to the .apk file instead
• the whole dependency tree with those changes get installed into the .pmbootstrap universe
• the explicitly required packages get added to world
• the .pmbootstrap universe gets removed again

This causes my /etc/apk/world in my phosh pinephone install to have >100 packages in it.

New behavior:

• pmbootstrap still builds the full dependency tree
• the tree gets checked against the local builds, ONLY the .apks that exist get added to the list
• the local .apks get installed into the .pmbootstrap universe, all their dependencies get added inexcplicitly now.
• normal install process occurs like above and the universe get removed.

Now I'm down to 6 packages in world. the .apk files in apk add don't seem to get added to /etc/apk/world and the dependencies that would get added aren't because now they're not explicit anymore.

Fixes: #1865 (closed)