support extracting zip archives

[Max Fisher]

Some packages such as proactive-jupyter-kernel upload their source as a zip file which currently fails as the static analysis archive extraction expects a .tar.gz file.

We should do filetype detection using file (NOT the file extension) so that we can do static analysis on zip archives too

[Gábor Lipták]

code to be updated seem to be at

package-analysis/internal/utils/archive_extract.go

Line 16 in c473e2d

 func ExtractTarGzFile(tgzPath string, outputDir string) error { 

might you be open to introducing something like https://github.com/mholt/archiver?

[Max Fisher]

Hi @gliptak, yes that's a good suggestion! I'd be open to introducing something like that. Please feel free to submit a PR.