Description: Fetch the value of the accrued governance fee. Note: this is often referred to as the Stability Fee, even though technically the Stability Fee is the fee that is paid in Dai, and the Governance Fee is the fee that is paid in MKR. But since fees are only paid in MKR in Single-Collateral Dai, and only paid in Dai in Multi-Collateral Dai, the fee in Single-Collateral Dai is often referred to as the Stability Fee to be consistent with the term that will be used in Multi-Collateral Dai and to avoid unduly confusing regular users.