Add pubkey setup for datacenter nodes (#5514)

net/scripts/add-testnet-solana-user-authorized_keys.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -ex
+
+[[ $(uname) = Linux ]] || exit 1
+[[ $USER = root ]] || exit 1
+
+[[ -d /home/solana/.ssh ]] || exit 1
+
+cd "$(dirname "$0")"
+
+# shellcheck source=net/scripts/solana-user-authorized_keys.sh
+source solana-user-authorized_keys.sh
+
+# solana-user-authorized_keys.sh defines the public keys for users that should
+# automatically be granted access to ALL testnets.
+for key in "${SOLANA_PUBKEYS[@]}"; do
+  echo "$key" >> /solana-authorized_keys
+done
+
+sudo -u solana bash -c "
+  cat /solana-authorized_keys >> /home/solana/.ssh/authorized_keys
+"