replace solana_sdk::pubkey with solana_pubkey in gossip

[kevinheavey]

Problem

This crate uses solana_sdk in many places. It will take multiple PRs to replace it everywhere

Summary of Changes

Find and replace solana_sdk::pubkey with solana_pubkey

[gregcusack]

is the end goal to get rid of solana_sdk from gossip all together? with the overall goal of reducing compile time/binary size?

[kevinheavey]

is the end goal to get rid of solana_sdk from gossip all together? with the overall goal of reducing compile time/binary size?

Yes

[gregcusack]

lgtm!