Sign shreds on the GPU (#6595)

* sign gpu shreds

* wip

* checks

* tests build

* test

* tests

* test

* nits

* sign cpu test

* write out the sigs in parallel

* clippy

* cpu test

* prepare secret for gpu

* woot!

* update

* bump perf libs

sdk/src/pubkey.rs

@@ -58,6 +58,9 @@ impl Pubkey {
             sol_log_64(0, 0, 0, i as u64, u64::from(*k));
         }
     }
+    pub fn to_bytes(self) -> [u8; 32] {
+        self.0
+    }
 }
 
 impl AsRef<[u8]> for Pubkey {