scripts: T6877: add a script for merging multiple flavor files

[dmbaturin]

Change Summary

Add a script for merging multiple flavor definition together.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

Component(s) name

Utils.

Proposed changes

To build source tarballs for releases, we need a way to collect all packages for all flavors included in a release. The simplest way to do that is likely to automatically produce a "meta-flavor", run its build, collect packages that were pulled from the repos during the build process, and discard the ISO.

This script uses custom (very simple) dict merging in case we need funny fixups down the line. It may be safe to use dict merging functions from vyos-1x, if proven safe, it will be a very simple change.

How to test

./scripts/utils/merge-flavors generic.toml <more files>

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

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