feat: mach-o certificate parsing implemented

[latonis]

With indygreg/cryptography-rs#21 being merged in now, we can have a much smaller dependency tree without reqwest and similar that were causing problems that caused the revert in 154994e for parsing certificates in mach-o binaries.

With not much progress for BER encoded certificates being made in RustCrypto/formats#779, I felt this was worth adding for the capability to search certificates in mach-o 😸

[plusvic]

I still have concerns about introducing another set of dependencies that implement an ASN parser. Depending on different sets of crates that implement basically the same are far from ideal.

I don't recall which was the issue we were trying to solve here, but I think that in the der_parser crate we already have the tools needed for parsing BER encoded certificates, as long we implement the required ASN structures by ourselves.

[latonis]

I still have concerns about introducing another set of dependencies that implement an ASN parser. Depending on different sets of crates that implement basically the same are far from ideal.

I don't recall which was the issue we were trying to solve here, but I think that in the der_parser crate we already have the tools needed for parsing BER encoded certificates, as long we implement the required ASN structures by ourselves.

Yeah, that's a fair concern. I can take a look at using der_parser and implementing the needed parts myself. 😄