2D spherical geometry

[zingale]

We want to add 2D spherical geometry $(r, \theta)$ on the grid with axisymmetry in $\phi$.

The following tasks need to be done:

• update the geometry source terms in Castro/Source/sources/Castro_geom.cpp to have the geometric terms (done in add geometric source terms for 2D spherical geometry #2955)
• add the primitive variable source terms (perhaps via add geometric source terms to the PPM tracing #2473) and ensure that d/dtheta has 1/r in interface prediction (done in update primitive variable reconstruction with spherical 2d geometry. #2964)
• make sure that the geometry terms are included in the transverse flux correction functions (done in address 2d spherical transverse correction #2961)
• add the geometry factors to diffusion
• update artifical viscosity (done in update divu calculation for spherical 2D geometry #2954)
• update the shock detection algorithm (done in update the shock detection algorithm for r-theta #2959)
• add the correct cross product for the Coriolis force in the rotational source term (done in address rotation source in spherical 2d coordinate #2967)
• update AMReX to know about the area and volume factors (done in add geometric terms for spherical 2D support. AMReX-Codes/amrex#4141)
• make constant gravity work in the radial direction (done in make const_grav in the r direction for 2D r-theta #2957)
• update our local area and volume functions (in Castro_util.H) to have the same factors (done in update local area and volume calculations for 2D spherical geometry #2953)
• address mom_flux_has_p (done in update mom_flux_has_p to address with 2D spherical #2958)
• add a ptheta flux register analogous to the pradial one (done in add P_theta flux register and scale pressure using area and volume #2960)
• make sure that the interpolation in AMReX uses the edge volume weights (these were inlined--see discussion in add geometric terms for spherical 2D support. AMReX-Codes/amrex#4141)
• update the timestep computation (to use r dtheta) (done in address timestep and cfl violation for Spherical2D #2962)

[zhichen3]

I think also update mom_flux_has_p and related stuff

[zhichen3]

also need to modify cfl_violation/timestep constraint since in spherical2d dy is just dtheta but we want physical length , so rdtheta, when checking and determining timestep