Migrate derivative to educe (#8125)

Fixes #7001.


  Mostly mechanical replacement of `derivative` attributes with `educe` ones.

### **Attribute Syntax Changes**

```rust
// Bounds: = "..." → (...)
#[derivative(Hash(bound = "E: EthSpec"))]
#[educe(Hash(bound(E: EthSpec)))]

// Ignore: = "ignore" → (ignore)
#[derivative(PartialEq = "ignore")]
#[educe(PartialEq(ignore))]

// Default values: value = "..." → expression = ...
#[derivative(Default(value = "ForkName::Base"))]
#[educe(Default(expression = ForkName::Base))]

// Methods: format_with/compare_with = "..." → method(...)
#[derivative(Debug(format_with = "fmt_peer_set_as_len"))]
#[educe(Debug(method(fmt_peer_set_as_len)))]

// Empty bounds: removed entirely, educe can infer appropriate bounds
#[derivative(Default(bound = ""))]
#[educe(Default)]

// Transparent debug: manual implementation (educe doesn't support it)
#[derivative(Debug = "transparent")]
// Replaced with manual Debug impl that delegates to inner field
```

**Note**: Some bounds use strings (`bound("E: EthSpec")`) for superstruct compatibility (`expected ','` errors).


Co-Authored-By: Javier Chávarri <javier.chavarri@gmail.com>

Co-Authored-By: Mac L <mjladson@pm.me>

common/eth2/src/lib.rs

@@ -19,7 +19,7 @@ pub use self::error::{Error, ok_or_error, success_or_error};
 use self::mixin::{RequestAccept, ResponseOptional};
 use self::types::*;
 use ::types::beacon_response::ExecutionOptimisticFinalizedBeaconResponse;
-use derivative::Derivative;
+use educe::Educe;
 use futures::Stream;
 use futures_util::StreamExt;
 use libp2p_identity::PeerId;
@@ -135,10 +135,10 @@ impl Timeouts {
 
 /// A wrapper around `reqwest::Client` which provides convenience methods for interfacing with a
 /// Lighthouse Beacon Node HTTP server (`http_api`).
-#[derive(Clone, Debug, Derivative)]
-#[derivative(PartialEq)]
+#[derive(Clone, Debug, Educe)]
+#[educe(PartialEq)]
 pub struct BeaconNodeHttpClient {
-    #[derivative(PartialEq = "ignore")]
+    #[educe(PartialEq(ignore))]
     client: reqwest::Client,
     server: SensitiveUrl,
     timeouts: Timeouts,