Add CI task to verify peer connectivity

## Context

There are several open PRs that add/remove/modify a peer address in peers.txt. Examples:

1. https://github.com/celestiaorg/networks/pull/525
2. https://github.com/celestiaorg/networks/pull/524
3. https://github.com/celestiaorg/networks/pull/521
4. https://github.com/celestiaorg/networks/pull/519
5. https://github.com/celestiaorg/networks/pull/509
6. https://github.com/celestiaorg/networks/pull/508
7. https://github.com/celestiaorg/networks/pull/507

## Problem

It's not immediately obvious how to verify the correctness of these PRs

## Proposal

Add a CI check that verifies if a peer is accessible and running on the network that corresponds to the `peers.txt` that was modified in the PR.