Add suport for cosine squared angle potential

[chrisjonesBSU]

Describe the behavior you would like added to GMSO
We should add support for the cosine squared angle potential
https://hoomd-blue.readthedocs.io/en/v5.3.1/hoomd/md/angle/cosinesquared.html

It is used by the dreiding forcefield, and we are thinking about adding support for that for the purposes of mBuild energy minimization, and possibly for offering complete support for Dreiding in GMSO.

[laowang-os]

Since MosDef is officially recommended by LAMMPS as an important and powerful Pre/Post Processing Tools, so I think it would be helpful to provide a workflow (or tutorial) for generating data files that can be used directly in LAMMPS MD calculations, like Moltemplate. And it would be better for more details about the problems may be confronted in this process, such as:
How to check the missing parameters?
How to add missing parameters in LAMMPS-readbale formats?
Is it necessary run a geometry optimization in DFT calculation after build a structure file like pdb and before apply the force field ?

Thanks for your work!