Replace system config Index for Nonce (#14290)

* replace Index by Nonce

* replace Index by Nonce

* replace Index by Nonce

* replace Index by Nonce

* replace Index by Nonce

* wip

* remove index in lieu of nonce

* wip

* remove accountnonce in lieu of nonce

* add minor improvement

* rebase and merge conflicts

substrate/bin/node/primitives/src/lib.rs

@@ -46,7 +46,7 @@ pub type Balance = u128;
 pub type Moment = u64;
 
 /// Index of a transaction in the chain.
-pub type Index = u32;
+pub type Nonce = u32;
 
 /// A hash of some data used by the chain.
 pub type Hash = sp_core::H256;