Tidy formatting of Reqwest errors (#4336)

## Issue Addressed

NA

## Proposed Changes

Implements the `PrettyReqwestError` to wrap a `reqwest::Error` and give nicer `Debug` formatting. It also wraps the `Url` component in a `SensitiveUrl` to avoid leaking sensitive info in logs.

### Before

```
Reqwest(reqwest::Error { kind: Request, url: Url { scheme: "http", cannot_be_a_base: false, username: "", password: None, host: Some(Domain("localhost")), port: Some(9999), path: "/eth/v1/node/version", query: None, fragment: None }, source: hyper::Error(Connect, ConnectError("tcp connect error", Os { code: 61, kind: ConnectionRefused, message: "Connection refused" })) })
```

### After

```
HttpClient(url: http://localhost:9999/, kind: request, detail: error trying to connect: tcp connect error: Connection refused (os error 61))
```

## Additional Info

I've also renamed the `Reqwest` error enum variants to `HttpClient`, to give people a better chance at knowing what's going on. Reqwest is pretty odd and looks like a typo.

I've implemented it in the `eth2` and `execution_layer` crates. This should affect most logs in the VC and EE-related ones in the BN.

I think the last crate that could benefit from the is the `beacon_node/eth1` crate. I haven't updated it in this PR since its error type is not so amenable to it (everything goes into a `String`). I don't have a whole lot of time to jig around with that at the moment and I feel that this PR as it stands is a significant enough improvement to merge on its own. Leaving it as-is is fine for the time being and we can always come back for it later (or implement in-protocol deposits!).

common/eth2/src/lighthouse_vc/http_client.rs

@@ -170,7 +170,7 @@ impl ValidatorClientHttpClient {
             .map_err(|_| Error::InvalidSignatureHeader)?
             .to_string();
 
-        let body = response.bytes().await.map_err(Error::Reqwest)?;
+        let body = response.bytes().await.map_err(Error::from)?;
 
         let message =
             Message::parse_slice(digest(&SHA256, &body).as_ref()).expect("sha256 is 32 bytes");
@@ -222,7 +222,7 @@ impl ValidatorClientHttpClient {
             .headers(self.headers()?)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         ok_or_error(response).await
     }
 
@@ -236,7 +236,7 @@ impl ValidatorClientHttpClient {
             .await?
             .json()
             .await
-            .map_err(Error::Reqwest)
+            .map_err(Error::from)
     }
 
     /// Perform a HTTP GET request, returning `None` on a 404 error.
@@ -266,7 +266,7 @@ impl ValidatorClientHttpClient {
             .json(body)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         ok_or_error(response).await
     }
 
@@ -297,7 +297,7 @@ impl ValidatorClientHttpClient {
             .json(body)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         let response = ok_or_error(response).await?;
         self.signed_body(response).await?;
         Ok(())
@@ -316,7 +316,7 @@ impl ValidatorClientHttpClient {
             .json(body)
             .send()
             .await
-            .map_err(Error::Reqwest)?;
+            .map_err(Error::from)?;
         ok_or_error(response).await
     }