Reduce the use of programs, default to `p7zip` on unix

As the title suggests, most operations can be done using the `7z` command. Archiving as `zip`, or `tar` doesn't require those commands. E.g. ```sh # compress into tar 7z a -ttar test.tar test_1.toml test_2.toml ... ``` ```sh # compress into zip 7z a -ttar test.zip test_1.toml test_2.toml ... ``` Let me know if there's a specific reason, or cons to this approach. Otherwise I'm happy to contribute a PR.