Enable split apks for debug builds

APKs for each architecture and a universal APK that is compatible for all architectures will now be available from Github Actions page from the workflow runs labeled `Build`. The APKs will be available as zips under the Artifact section named `termux-app-*`.

Architecture specific APKs can be used by users with low disk space since F-Droid releases are universal (since it doesn't support split APKs #1904) and their install+bootstrap installation size is ~180MB instead of ~120MB if an architecture specific APK is used.

This should also reduce bandwidth usage and download time for debug builds users if they download an architecture specific zip instead of the universal one.

Related #2153