ENH: turbulentMixingLengthDissipationRateInlet Cmu lookup for realizableKE

In turbulentMixingLengthDissipationRateInletFvPatchScalarField.C Cmu appears to be looked up or defaulted to a constant of 0.09...

// Lookup Cmu corresponding to the turbulence model selected
    const turbulenceModel& turbModel = db().lookupObject<turbulenceModel>
    (
        IOobject::groupName
        (
            turbulenceModel::propertiesName,
            internalField().group()
        )
    );

    const scalar Cmu =
        turbModel.coeffDict().lookupOrDefault<scalar>("Cmu", 0.09);

It looks like Cmu is being looked up from the turbulence dictionary in turbulenceProperties. However, for turbulence models like realizableKE where Cmu is not constant, I think Cmu should be looked up from the turbulence model itself. Am I reading this correctly? Thoughts?

## Reattaching the author to the issue ticket: @graups ##