Add peer-status to wireguard peer metrics

[tjdavis3]

Description

This change adds the peer-status as opnsense_wireguard_peer_status. This will allow alerting based on peer status and a way of alerting when the interface is up but the peer is offline.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Checklist:

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• I have updated the docs/metrics.md file, when I introduced new metrics
• I have commented my code, particularly in hard-to-understand areas
• New and existing unit tests pass locally with my changes