ENH: replace finiteArea timeVaryingUniformFixedValue with Function1 version

- timeVaryingUniformFixedValue -> uniformFixedValue

- allows a variety of functions (eg, coded, expressions, tables, ...)

- more similarity to finiteVolume patch type

STYLE: remove unused timeVarying... from etc/controlDict

etc/controlDict

@@ -903,10 +903,7 @@ DebugSwitches
     thermophysicalFunction 0;
     time                0;
     timeVaryingAlphaContactAngle 0;
-    timeVaryingFlowRateInletVelocity 0;
     timeVaryingMappedFixedValue 0;
-    timeVaryingTotalPressure 0;
-    timeVaryingUniformFixedValue 0;
     timer               0;
     topoAction          0;
     topoCellLooper      0;