tests/fuzzers: move fuzzers into native packages (#28467)

This PR moves our fuzzers from tests/fuzzers into whatever their respective 'native' package is.

The historical reason why they were placed in an external location, is that when they were based on go-fuzz, they could not be "hidden" via the _test.go prefix. So in order to shove them away from the go-ethereum "production code", they were put aside.

But now we've rewritten them to be based on golang testing, and thus can be brought back. I've left (in tests/) the ones that are not production (bls128381), require non-standard imports (secp requires btcec, bn256 requires gnark/google/cloudflare deps).

This PR also adds a fuzzer for precompiled contracts, because why not.

This PR utilizes a newly rewritten replacement for go-118-fuzz-build, namely gofuzz-shim, which utilises the inputs from the fuzzing engine better.

go.mod

@@ -33,7 +33,7 @@ require (
 	github.com/golang-jwt/jwt/v4 v4.5.0
 	github.com/golang/protobuf v1.5.3
 	github.com/golang/snappy v0.0.5-0.20220116011046-fa5810519dcb
-	github.com/google/gofuzz v1.1.1-0.20200604201612-c04b05f3adfa
+	github.com/google/gofuzz v1.2.0
 	github.com/google/uuid v1.3.0
 	github.com/gorilla/websocket v1.4.2
 	github.com/graph-gophers/graphql-go v1.3.0