Mac L fd55373b88 Add new VC metrics for beacon node availability (#3193) ...

## Issue Addressed

#3154 

## Proposed Changes

Add three new metrics for the VC:
1. `vc_beacon_nodes_synced_count`
2. `vc_beacon_nodes_available_count`
3. `vc_beacon_nodes_total_count`

Their values mirror the values present in the following log line:
```
Apr 08 17:25:17.000 INFO Connected to beacon node(s) synced: 4, available: 4, total: 4, service: notifier
```

2022-05-26 02:05:16 +00:00

..

slashing_protection

Replace OpenOptions::new with File::options to be readable (#3059)

2022-03-07 06:30:18 +00:00

src

Add new VC metrics for beacon node availability (#3193)

2022-05-26 02:05:16 +00:00

Cargo.toml

Update and consolidate dependencies (#3136)

2022-04-04 00:26:16 +00:00