Add SensitiveUrl to redact user secrets from endpoints (#2326)

## Issue Addressed

#2276 

## Proposed Changes

Add the `SensitiveUrl` struct which wraps `Url` and implements custom `Display` and `Debug` traits to redact user secrets from being logged in eth1 endpoints, beacon node endpoints and metrics.

## Additional Info

This also includes a small rewrite of the eth1 crate to make requests using `Url` instead of `&str`. 
Some error messages have also been changed to remove `Url` data.

beacon_node/genesis/tests/tests.rs

@@ -7,6 +7,7 @@ use environment::{Environment, EnvironmentBuilder};
 use eth1::{DEFAULT_CHAIN_ID, DEFAULT_NETWORK_ID};
 use eth1_test_rig::{DelayThenDeposit, GanacheEth1Instance};
 use genesis::{Eth1Config, Eth1GenesisService};
+use sensitive_url::SensitiveUrl;
 use state_processing::is_valid_genesis_state;
 use std::time::Duration;
 use tokio_compat_02::FutureExt;
@@ -46,7 +47,7 @@ fn basic() {
 
             let service = Eth1GenesisService::new(
                 Eth1Config {
-                    endpoints: vec![eth1.endpoint()],
+                    endpoints: vec![SensitiveUrl::parse(eth1.endpoint().as_str()).unwrap()],
                     deposit_contract_address: deposit_contract.address(),
                     deposit_contract_deploy_block: now,
                     lowest_cached_block_number: now,