ENH: outletMappedUniformInlet: add optional fraction and offset

Summary

The new functionality optionally allows the patch-averaged value to be scaled and/or offset by a pair of specified values.

Example of the boundary condition specification:

<patchName>
{
    // Mandatory entries (unmodifiable)
    type            outletMappedFilterInlet;
    outletPatch     <outletPatchName>;
    
    // Optional entries (unmodifiable)
    fraction        0.1;
    offset          10;    // (1 0 0);
    phi             phi;
    
    // Optional (inherited) entries
    ...
}

Details of new models

The tutorial airRecirculationRoom and related visualisations are exclusively prepared by Alseny Diallo.

Risks

• The bug fix may further need to be tested.
• No change to user input.