Add ICZ and Arctic Network to the Nexus portal

[andrii-kl]

Overview

Add ICZ and Arctic Network to the Nexus portal

Story

As a Nexus user, I want Arctic testnet and ICZ token on Nexus so that I can transfer ICZ across networks connected to ICON Bridge using Nexus

Acceptance Criteria

• I can send the ICZ token to networks connected to the ICON Bridge via Nexus

[CyrusVorwald]

Transferring issue to Nexus repo