Added serialize and deserialize to starky proofs

[armanthepythonguy]

Added serialize and deserialize to starky proofs. We needed this for our ZKML project where we needed to export the proofs into files and read them back to verify. It might be useful for other projects as well !!!

[muursh]

@armanthepythonguy can you fix the clippy issue then we'll merge

[armanthepythonguy]

@armanthepythonguy can you fix the clippy issue then we'll merge

I tried running cargo clippy and I got this
warning[E0602]: unknown lint: clippy::too_long_first_doc_paragraph
|
= note: requested on the command line with -A clippy::too_long_first_doc_paragraph
= note: #[warn(unknown_lints)] on by default

For more information about this error, try rustc --explain E0602.
warning: plonky2_field (lib) generated 1 warning
Checking plonky2 v0.2.2 (/Users/armanaurobindo/Desktop/plonky2/plonky2)
warning: plonky2 (lib) generated 1 warning (1 duplicate)
Checking starky v0.4.0 (/Users/armanaurobindo/Desktop/plonky2/starky)
warning: starky (lib) generated 1 warning (1 duplicate)
Finished dev profile [unoptimized + debuginfo] target(s) in 6.40s

Also I ran cargo fmt and got no changes. Can you please have a look? @Nashtare @muursh

[Nashtare]

@armanthepythonguy you need latest nightly toolchain for this to be triggered

[Nashtare]

Thank you!