SIR #01: Allow DynaSets to hold additional stablecoins.

Add the ability for Dynasets to hold USDT, USDC, DAI, BUSD, TUSD, USDP, FRAX, EURT. The acceptance of this proposal would allow the relevant DynaSets (dynBTC, dynETH, dynETHc, dynL1BNB) to diversify stablecoin holdings in order to mitigate stablecoin-related risks such as de-peg or lack of liquidity. The proposal would also allow DynaSets to be ready in general for any token de-pegs including wrapped assets. This will provide access to a more diversified portfolio of stablecoins, which will help to reduce the impact of any one stablecoin de-pegging.