Nek5000 to nekRS variable conversion

[JezSw]

Some table of strict variable name/location changes would benefit intermediate and above 5000 users quickly convert some examples to RS.

[kzscisoft]

In the form <parent-function>:<variable>:

Nek5000	NekRS
NEKUSE:ux	codedFixedValueVelocity:bc->u
NEKUSE:uy	codedFixedValueVelocity:bc->v
NEKUSE:uz	codedFixedValueVelocity:bc->w
GEOM:ym1(i,1,1,1)	UDF_Setup:nrs->meshV->y[i]
ntot=SIZE:nelt*lx1*ly1*lz1	UDF_Setup:nrs->meshV->Nlocal
NEKNEK:valint(..., 1)	codedFixedValueVelocity:bc->uinterp
NEKNEK:valint(..., 2)	codedFixedValueVelocity:bc->vinterp
NEKNEK:valint(..., 3)	codedFixedValueVelocity:bc->winterp
ffx = <val>	platform->linAlg->fill(nrs->meshV->Nlocal, <val>, nrs->o_NLT + 0 * nrs->fieldOffset)

[kzscisoft]

Difference in execution of multiple meshes combined, for Nek5000:

neknekb <components ...> <ranks...>

For Nekrs:

nekbmpi <session-file> <n-ranks>

[JezSw]

@kzscisoft does this need looking at?