Reduce the use of programs, default to p7zip on unix

[v3natio]

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.

# compress into tar
7z a -ttar test.tar test_1.toml test_2.toml ...

# 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.

[KKV9]

I think the code can be simplified using this approach. Features such as password-protected archives will be easier to implement, though at the expense of creating an additional dependency for Unix users. If possible, consider keeping the initial Unix options as a backup for those who do not have p7zip installed. We can fully deprecate them at a later stage. Thanks.