Update Gameplay Token List

Background

Today, MANA, DAI, ETH, USDT, and ATRI are the available gameplay options. MANA and DAI were available at product launch, and ATRI, ETH, and USDT were added in February, March, and April, respectively.

Today, we have 183K USDT and 415K ATRI (~$27K) backing bets for these tokens in the Gameplay Treasury. [Note: ATRI price has declined substantially since the token was added].

At the same time, there has been interest from the community in adding $DG as a gameplay token for some time now, and there's also some interest in the new ICE token being available for gameplay.

Proposal

-- Add $DG & ICE as gameplay options -- Back $DG bets with $150K out of $DG Treasury -- Back ICE bets with $150K out of initial ICE supply -- Remove USDT & ATRI as gameplay options -- Convert the ~$210K worth of USDT & ATRI in the gameplay treasury to USDC, pair with ICE, and provide ~$420K LP to the USDC-ICE pair on QuickSwap

Rationale

Looking at USD-value gameplay volumes since May 1st, the distribution is as follows, and it's clear we're not getting significant use out of USDT or ATRI:

-- MANA: 40.9% -- DAI: 31.3% -- ETH: 23.1% -- USDT: 3.5% -- ATRI: 1.2%

Making $DG and ICE available as options would add additional utility to the tokens, and ~$420K incremental USDC-ICE LP is more useful to the DAO than availability of USDT & ATRI gameplay.

Whether or ICE profits should be burned in order to produce deflationary pressure on the token will be left for a future proposal.