Update graphql pending to allow txn sorting (#1450)

* Update graphql pending to allow for sorting of transactions

Signed-off-by: David Mechler <david.mechler@consensys.net>

ethereum/api/src/main/resources/schema.graphqls

@@ -257,12 +257,21 @@ type SyncState{
     knownStates: Long
 }
 
+input TransactionOrderByNonce {
+    nonce: Sort
+}
+
+enum Sort {
+    asc
+    desc
+}
+
 # Pending represents the current pending state.
 type Pending {
   # TransactionCount is the number of transactions in the pending state.
   transactionCount: Int!
   # Transactions is a list of transactions in the current pending state.
-  transactions: [Transaction!]
+  transactions(orderBy: TransactionOrderByNonce): [Transaction!]
   # Account fetches an Ethereum account for the pending state.
   account(address: Address!): Account!
   # Call executes a local call operation for the pending state.

ethereum/api/src/test/resources/org/hyperledger/besu/ethereum/api/graphql/graphql_pending.json

@@ -1,6 +1,6 @@
 {
   "request":
-    "{ pending { transactionCount transactions { nonce gas } account(address:\"0x6295ee1b4f6dd65047762f924ecd367c17eabf8f\") { balance} estimateGas(data:{}) call (data : {from : \"0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b\", to: \"0x6295ee1b4f6dd65047762f924ecd367c17eabf8f\", data :\"0x12a7b914\"}){data status}} }",
+    "{ pending { transactionCount transactions(orderBy: {nonce: asc}) { nonce gas } account(address:\"0x6295ee1b4f6dd65047762f924ecd367c17eabf8f\") { balance} estimateGas(data:{}) call (data : {from : \"0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b\", to: \"0x6295ee1b4f6dd65047762f924ecd367c17eabf8f\", data :\"0x12a7b914\"}){data status}} }",
 
   "response": {
     "data": {