Update Heco chain

[JamesSmartCell]

• Heco Testnet is no longer running; remove it.
• Heco Mainnet RPC: https://http-mainnet-node.huobichain.com
• Heco Logo:

[hboon]

@JamesSmartCell Do you know if Hubo chain is still running? All these sites don't seem to work:

• https://hecoscan.io/#/
• https://www.hecochain.com
• https://hecoinfo.com
• http://www.huobichain.com
• https://http-mainnet-node.huobichain.com (RPC?)