pmb.parse.apkindex: Introduce proper typing

pmb/aportgen/busybox_static.py

pmb/aportgen/core.py

pmb/build/_package.py

pmb/build/other.py

pmb/chroot/apk.py

pmb/chroot/apk_static.py

pmb/chroot/test_apk.py

pmb/chroot/zap.py

pmb/helpers/frontend.py

pmb/helpers/package.py

pmb/helpers/pkgrel_bump.py

pmb/helpers/pmaports.py

pmb/install/_install.py

pmb/parse/apkindex.py

pmb/sideload/__init__.py