AsterX dependency in AsterSeeds

[SamuelCupp]

Currently, AsterSeeds can only set initial data for AsterX. This isn't ideal, as it would be nice to have a general-purpose thorn for ID instead of having multiple. This issue is connected to a related CarpetX issue.

As stated in that issue, one solution would be to move Avec to HydroBaseX. This requires the ability to set the rhs tag for these variables at runtime, which may not be currently supported.

Alternatively, AsterSeeds could use the method of VolumeIntegrals_vacuum to change which variable it is accessing via a CCTK_STRING parameter. However, I am not sure how this method will interact with the new tiling/parallelism in CarpetX.

[SamuelCupp]

For now, I'm adding a thorn to my repo (not pushed to remote yet) that provides the same functionality as AsterSeeds but depends on GRHayLET. Since I'm not doing magnetic fields yet, I don't have to worry about Avec, and it doesn't depend on GRHayLHDX. I have tried to prune the code and make it more like I want it to look.

Right now it only has the 1D tests, but it does the switching of test types and directions in a cleaner way (in my opinion). I also split the hydro and Avec ID into two different functions, though all the actual Avec code is commented out. This is so we could have pure hydro ID for cases where a code doesn't evolve magnetic fields.

If we get to a point where we want to only have one version, we can talk about which thorn seems to be in a better state and make a single ID thorn.