[zk-sdk] Create zk-sdk crate

[samkim-crypto]

Problem

There are a number of breaking changes that must be made to the solana-zk-token-sdk (#671) that break downstream (essentially just spl). To lift the CI spl downstream check, we need to wait until we have a v2.0 release. However, confidential transfers in the token extensions is high priority and it would be really great if we can include these changes as part of the v2.0 release. Furthermore, the necessary changes we would need includes renaming solana-zk-token-sdk to solana-zk-sdk. It would actually make things a lot simpler if we publish a new solana-zk-sdk, migrate the logic from solana-zk-token-sdk to it, and then deprecate solana-zk-token-sdk in the future.

Summary of Changes

Create the zk-sdk crate. I don't have anything in the crate yet. Each submodules from the zk-token-sdk will be moved into the new crate incrementally.

Fixes #

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.9%. Comparing base (f133697) to head (12140b4).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #988   +/-   ##
=======================================
  Coverage    81.9%    81.9%           
=======================================
  Files         855      856    +1     
  Lines      232134   232135    +1     
=======================================
+ Hits       190134   190150   +16     
+ Misses      42000    41985   -15