Remove Oracle Swap Freezer Underlying Check

[efecarranza]

The OracleSwapFreezer contract has a check on construction to ensure that the GSM's underlying asset is the same that will be used as oracle for the GSM.

require(gsm.UNDERLYING_ASSET() == underlyingAsset, 'UNDERLYING_ASSET_MISMATCH');

While this check worked initially for regular underlying GSMs, for GSM4626, this check does not work as the underlying might be different: for example, a Static A Token USDC GSM won't have a stataUSDC oracle available, making it impossible to deploy the OracleSwapFreezer.

This check can be removed as the underlying asset might not be the one to be used as an oracle.