script for vendoring maven dependencies from pom.xml

[MoralCode]

For Maven, flatpak/flatpak-builder#58 (comment) is probably useful to know about (and used by some existing apps on Flathub).

Originally posted by @wvengen in #37

I noticed the original issue listed maven and gradle but was closed when gradle support was added. since ive started experimenting with this on my fork (not yet ready to contribute) and since I found this comment helpful, I wanted to make a separate issue to track progress

[MoralCode]

so far i have a script that can seemingly output links to dependency parts from the repo.maven.apache.org repo (but still needs to generate hashes for them to be fully valid as a flatpak source)

[lenucksi]

I build something that will run mvn clean package with a fresh .m2 repo and build the dependency list based on the built .m2 repo and Maven script output: https://github.com/lenucksi/SieveEditor/blob/master/scripts/fetch-maven-deps-for-flatpak.sh

I've run it against a sandboxed Maven build and Maven was happy inside it.