Get arbitrary check passing (2.0) (#2710)

## Issue Addressed

NA

## Proposed Changes

This is a wholesale rip-off of #2708, see that PR for more of a description.

I've made this PR since @realbigsean is offline and I can't merge his PR due to Github's frustrating `target-branch-check` bug. I also changed the branch to `unstable`, since I'm trying to minimize the diff between `merge-f2f`/`unstable`. I'll just rebase `merge-f2f` onto `unstable` after this PR merges.

When running `make lint` I noticed the following warning:

```
warning: patch for `fixed-hash` uses the features mechanism. default-features and features will not take effect because the patch dependency does not support this mechanism
```

So, I removed the `features` section from the patch.

## Additional Info

NA


Co-authored-by: realbigsean <seananderson33@gmail.com>

consensus/ssz_types/Cargo.toml

@@ -16,7 +16,7 @@ serde_derive = "1.0.116"
 eth2_serde_utils = "0.1.0"
 eth2_ssz = "0.4.0"
 typenum = "1.12.0"
-arbitrary = { version = "0.4.6", features = ["derive"], optional = true }
+arbitrary = { version = "1.0", features = ["derive"], optional = true }
 
 [dev-dependencies]
 serde_json = "1.0.58"

consensus/ssz_types/src/bitfield.rs

@@ -644,7 +644,7 @@ impl<N: Unsigned + Clone> tree_hash::TreeHash for Bitfield<Fixed<N>> {
 }
 
 #[cfg(feature = "arbitrary")]
-impl<N: 'static + Unsigned> arbitrary::Arbitrary for Bitfield<Fixed<N>> {
+impl<N: 'static + Unsigned> arbitrary::Arbitrary<'_> for Bitfield<Fixed<N>> {
     fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
         let size = N::to_usize();
         let mut vec: Vec<u8> = vec![0u8; size];
@@ -654,7 +654,7 @@ impl<N: 'static + Unsigned> arbitrary::Arbitrary for Bitfield<Fixed<N>> {
 }
 
 #[cfg(feature = "arbitrary")]
-impl<N: 'static + Unsigned> arbitrary::Arbitrary for Bitfield<Variable<N>> {
+impl<N: 'static + Unsigned> arbitrary::Arbitrary<'_> for Bitfield<Variable<N>> {
     fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
         let max_size = N::to_usize();
         let rand = usize::arbitrary(u)?;

consensus/ssz_types/src/fixed_vector.rs

@@ -280,8 +280,10 @@ where
 }
 
 #[cfg(feature = "arbitrary")]
-impl<T: arbitrary::Arbitrary, N: 'static + Unsigned> arbitrary::Arbitrary for FixedVector<T, N> {
-    fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+impl<'a, T: arbitrary::Arbitrary<'a>, N: 'static + Unsigned> arbitrary::Arbitrary<'a>
+    for FixedVector<T, N>
+{
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
         let size = N::to_usize();
         let mut vec: Vec<T> = Vec::with_capacity(size);
         for _ in 0..size {

consensus/ssz_types/src/variable_list.rs

@@ -259,8 +259,10 @@ where
 }
 
 #[cfg(feature = "arbitrary")]
-impl<T: arbitrary::Arbitrary, N: 'static + Unsigned> arbitrary::Arbitrary for VariableList<T, N> {
-    fn arbitrary(u: &mut arbitrary::Unstructured<'_>) -> arbitrary::Result<Self> {
+impl<'a, T: arbitrary::Arbitrary<'a>, N: 'static + Unsigned> arbitrary::Arbitrary<'a>
+    for VariableList<T, N>
+{
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
         let max_size = N::to_usize();
         let rand = usize::arbitrary(u)?;
         let size = std::cmp::min(rand, max_size);