Refactoring build system

[Tbaile]

The current build system has some limitations:

• You cannot switch easily between openwrt versions, needs a tag to be present
• Has been proven a bit inconsistent in the packages hashes
• Needs a Podman image to build, this means we need a image registry to build
• We cannot release a new image when we want, must follow OpenWRT versioning
• Override of the packages is hard

Issues found in this refactor so far:

• Need to change distfeed-setup entirely, check for regressions
• Change upload of dev branches, we can now switch easily between targets, this comes at the price of the mandatory handle of the S3 bucket with multiple branches
• Check if build time can be shrunk, it appears that rearranging the build feeds to override the packages, we have an increment in build time

[Tbaile]

QA:

Install one of the latest dev build, BUT NOT THE LATEST from here: https://github.com/NethServer/nethsecurity/actions?query=branch%3Amain

1. Fresh install

   1. Check if there are any updates (no issues should arise) and a new update should be available
   2. Enable a subscription, see that updates should prompt you to go back to 1.6.0
   3. Remove the subscription, check that status restores as previous

2. Update

   1. Update from a subscribed machine, check that cases from 1.ii are verified
   2. Update from a community machine, repeat test cases from 1