Update aztec playground

[critesjosh]

Update https://aztec-playground.netlify.app/ to include the following

• include a link for a tx to a block explorer (add a popup notification/modal for when the tx is completed)
• include the schnorr account contract artifact and token contract artifact
• css
• for testnet / devnet:
  • default connection will be to testnet
  • make the logs panel minimizable
  • point url to a new domain (aztec.network/playground ?)
• info explaining what is going on during deployment ("you are generating a proof for contract deployment, client side, for maximum privacy, etc. you can read more about client-side proving or contract deployment here (insert link)) add the info in this modal:

Stretch goal:

• make the account contract exportable
  • if someone closes the playground tab, they lose the account info for their deployed account contract
• add easy private voting contract (or other) to the playground defaults

Note (cc @rahul-kothari):

• we need to pre deploy the token contract to this network. unrestricted minting so people can mint themselves token
• pre-deploy sponsored FPC that works with everything