Remove Cardano-specific TxMeasure dimensions from abstract Consensus layer

[amesgen]

#1191 introduced an ad-hoc type class to the abstract Consensus layer

ouroboros-consensus/ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Ledger/SupportsMempool.hs

Lines 432 to 436 in 447ae7a

	class TxMeasureMetrics msr where
	txMeasureMetricTxSizeBytes :: msr -> ByteSize32
	txMeasureMetricExUnitsMemory :: msr -> Natural
	txMeasureMetricExUnitsSteps :: msr -> Natural
	txMeasureMetricRefScriptsSizeBytes :: msr -> ByteSize32

that is required by LedgerSupportsMempool blk. It is used only for the LocalTxMonitor server implementation.

The goal of this ticket is to remove this Cardano-specific notion from the abstract Consensus layer again, eg by changing the class to sth like

class TxMeasureMetrics msr where 
  txMeasureMetricTxSizeBytes :: msr -> Map MeasureName Natural