anchor-client update (#758)

* remove unused structopt

* cleanup anchor-lang dep

anchor-lang is re-exported through anchor-client.
and was unused in some projects.

* update anchor-lang 0.26 -> 0.27

RequestNamespace was removed
coral-xyz/anchor#2285

* update anchor-lang 0.27 -> 0.28

We don't use async feature in achor-lang, which means we get the blocking version of RequestBuilder. It needs a handle to the runtime to block with.

also ran `cargo update -p helium-anchor-gen` to get generated types to implement updated traits.

* update anchor-lang 0.28 -> 0.29

no code changes required

---------

Co-authored-by: Matthew Plant <maplant@protonmail.com>