Returns the resource-pressure level for key (config.gas.features[key]).
Returns GasLevel.Normal with zero overhead when the feature factor is 0 or absent
and no gas plugins are registered (plugins are always consulted and may escalate any key).
Restart the elapsed-time counter (called when the owning context is reset).
Checks heap and elapsed-time pressure for named analysis features. See ReadOnlyFlowrAnalyzerGasContext.