ATC: fix_modify AtC mesh quadrature

# fix_modify AtC mesh quadrature

## syntax

fix_modify AtC mesh quadrature <quad>

- quad = one of <nodal|gauss1|gauss2|gauss3|face> --- when a mesh is created it defaults to gauss2, use this call to change it after the fact

## examples

`fix_modify AtC mesh quadrature face`

## description

(Re-)assigns the quadrature style for the existing mesh.

## restrictions

## related

fix_modify AtC mesh create

## default

none