ENH: enable custom input of U for devRhoReff and devReff

Summary

• 874bc33f - BUG: forces: ensure UName entry can be used (fixes #2093 (closed))
• 2cd6071c - ENH: enable custom input of U for devRhoReff and devReff

Previously, for basic incompressible and compressible simulations, the "force" function object has not been using the user-specified "UName" for the "devRhoReff" computation (affecting the tangential component), but using the "U" of the latest available step. In contrast, the user-specified "pName" has always been being used correctly.

This has been causing issues for users when they wish to use a specific "UMean" field in various force and forceCoeff function object computations.

Also, the set of commits can allow the usage of custom U for other function objects, such as yPlus, wallShearStress etc.

Resolved bugs (If applicable)

#2093 (closed)

EP#1224

Risks

No risk expected.

Test cases

See 41c0fa3b in t-repo.