PR progress checklist (to be filled in by reviewers)

• Changes to documentation are appropriate (or tick if not required)
• Changes to tests are appropriate (or tick if not required)
• Reviews completed

What type of PR is this?

Primary type

• [build] Changes related to the build system
• [chore] Changes to the build process or auxiliary tools and libraries such as documentation generation
• [ci] Changes to the continuous integration configuration
• [feat] A new feature
• [fix] A bug fix
• [perf] A code change that improves performance
• [refactor] A code change that neither fixes a bug nor adds a feature
• [revert] A change used to revert a previous commit
• [style] Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc.)

Secondary type

• [docs] Documentation changes
• [test] Adding missing or correcting existing tests

Does this PR introduce a BREAKING CHANGE?

No.

Related issues and/or pull requests

Describe the changes you're proposing

Allow to specify custom repositories' filenames instead of the fixed ones <repo>-<type>.list.

For backward compatibility, if no filename is specified, the old behavior is honored.

Pillar / config required to test the proposed changes

apt:
  repositories:
    raspbian:
      filename: my_raspbian_repo.list
      distro: stable
      url: http://archive.raspbian.org/raspbian
      type: [source]
      key_url: https://archive.raspbian.org/raspbian.public.key

Debug log showing how the proposed changes work

Documentation checklist

• Updated the README (e.g. Available states).
• Updated pillar.example.

Testing checklist

• Included in Kitchen (i.e. under state_top).
• Covered by new/existing tests (e.g. InSpec, Serverspec, etc.).
• Updated the relevant test pillar.

Additional context