Electra: BeaconState implementation (#13919)

* Electra: Beacon State

* Electra: Beacon state fixes from PR 13919

* Add missing tests - part 1

* Split eip_7251_root.go into different files and reuse/share code with historical state summaries root. It's identical!

* Add missing tests - part 2

* deposit receipts start index getters and setters (#13947)

* adding in getters and setters for deposit receipts start index

* adding tests

* gaz

* Add missing tests - part 3 of 3

Update the electra withdrawal example with a ssz state containing pending partial withdrawals

* add tests for beacon-chain/state/state-native/getters_balance_deposits.go

* Add electra field to testing/util/block.go execution payload

* godoc commentary on public methods

* Fix failing test

* Add balances index out of bounds check and relevant tests.

* Revert switch case electra

* Instead of copying spectest data into testdata, use the spectest dependency

* Deepsource fixes

* Address @rkapka PR feedback

* s/MaxPendingPartialsPerWithdrawalSweep/MaxPendingPartialsPerWithdrawalsSweep/

* Use multivalue slice compatible accessors for validator and balance in ActiveBalanceAtIndex

* More @rkapka feedback. What a great reviewer!

* More tests for branching logic in ExitEpochAndUpdateChurn

* fix build

---------

Co-authored-by: james-prysm <90280386+james-prysm@users.noreply.github.com>

math/BUILD.bazel

@@ -5,7 +5,10 @@ go_library(
     srcs = ["math_helper.go"],
     importpath = "github.com/prysmaticlabs/prysm/v5/math",
     visibility = ["//visibility:public"],
-    deps = ["@com_github_thomaso_mirodin_intmath//u64:go_default_library"],
+    deps = [
+        "@com_github_prysmaticlabs_fastssz//:go_default_library",
+        "@com_github_thomaso_mirodin_intmath//u64:go_default_library",
+    ],
 )
 
 go_test(

math/math_helper.go

@@ -3,11 +3,13 @@ package math
 
 import (
 	"errors"
+	"fmt"
 	stdmath "math"
 	"math/big"
 	"math/bits"
 	"sync"
 
+	fssz "github.com/prysmaticlabs/fastssz"
 	"github.com/thomaso-mirodin/intmath/u64"
 )
 
@@ -216,9 +218,53 @@ func AddInt(i ...int) (int, error) {
 // Wei is the smallest unit of Ether, represented as a pointer to a bigInt.
 type Wei *big.Int
 
+var _ fssz.HashRoot = (Gwei)(0)
+var _ fssz.Marshaler = (*Gwei)(nil)
+var _ fssz.Unmarshaler = (*Gwei)(nil)
+
 // Gwei is a denomination of 1e9 Wei represented as an uint64.
 type Gwei uint64
 
+// HashTreeRoot --
+func (g Gwei) HashTreeRoot() ([32]byte, error) {
+	return fssz.HashWithDefaultHasher(g)
+}
+
+// HashTreeRootWith --
+func (g Gwei) HashTreeRootWith(hh *fssz.Hasher) error {
+	hh.PutUint64(uint64(g))
+	return nil
+}
+
+// UnmarshalSSZ --
+func (g *Gwei) UnmarshalSSZ(buf []byte) error {
+	if len(buf) != g.SizeSSZ() {
+		return fmt.Errorf("expected buffer of length %d received %d", g.SizeSSZ(), len(buf))
+	}
+	*g = Gwei(fssz.UnmarshallUint64(buf))
+	return nil
+}
+
+// MarshalSSZTo --
+func (g *Gwei) MarshalSSZTo(dst []byte) ([]byte, error) {
+	marshalled, err := g.MarshalSSZ()
+	if err != nil {
+		return nil, err
+	}
+	return append(dst, marshalled...), nil
+}
+
+// MarshalSSZ --
+func (g *Gwei) MarshalSSZ() ([]byte, error) {
+	marshalled := fssz.MarshalUint64([]byte{}, uint64(*g))
+	return marshalled, nil
+}
+
+// SizeSSZ --
+func (g *Gwei) SizeSSZ() int {
+	return 8
+}
+
 // WeiToGwei converts big int wei to uint64 gwei.
 // The input `v` is copied before being modified.
 func WeiToGwei(v Wei) Gwei {