all: simplify timestamps to uint64 (#19372)

* all: simplify timestamps to uint64

* tests: update definitions

* clef, faucet, mobile: leftover uint64 fixups

* ethash: fix tests

* graphql: update schema for timestamp

* ethash: remove unused variable

cmd/faucet/faucet.go

@@ -579,7 +579,7 @@ func (f *faucet) loop() {
 	go func() {
 		for head := range update {
 			// New chain head arrived, query the current stats and stream to clients
-			timestamp := time.Unix(head.Time.Int64(), 0)
+			timestamp := time.Unix(int64(head.Time), 0)
 			if time.Since(timestamp) > time.Hour {
 				log.Warn("Skipping faucet refresh, head too old", "number", head.Number, "hash", head.Hash(), "age", common.PrettyAge(timestamp))
 				continue