Salvage #17, update dependencies, add feature gates

[In-line]

Please, keep author attribution in squashed commit 4822256, I want to respect the work @stevefan1999-personal done.

1. PR use pure rust implementation to use as library #17 merged with squash as the basis commit.
2. Clippy warnings are fixed
3. There is feature gate for external and native download (external being default).
4. Dependencies are updates, as both zip-extract and sevenz-rust are unmaintained/deprecated (and are problematic, especially zip-extract which did minor version change with breaking changes)

I also created PR to add zip-extract to RUSTSEC DB rustsec/advisory-db#3160

Closes #17