TIP5P multiple virtual-types

[CalCraven]

Bug summary
Issue with handling multiple virtual-types in a forcefield. Essentially, since we're just loading based on the types connected with a "~", then we can't handle the TIP5P forcefield, which has two virtual types with parent atoms HW-OW-HW.

I would suggest we append the virtual_type.name as part of the key dictionary, which will allow for multiple types.

Code to reproduce the behavior

import gmso
ff = gmso.ForceField("gmso/utils/files/gmso_xmls/test_ffstyles/tip5p_2018.xml")
print(ff.virtual_types.keys())

dict_keys(['HW~OW~HW'])

Suggest Change

dict_keys(['HW~OW~HW-VirtualSiteType-3-sitea', 'HW~OW~HW-VirtualSiteType-3-siteb'])

Software versions

• Which version of GMSO are you using? (0.12.4`)
• Which version of Python (3.11)?
• Which operating system? (arm-64

[chrisjonesBSU]

This approach seems reasonable. We can mull it over some more after #890 is merged.

[CalCraven]

Just pinging this as ongoing work, maybe it's something @askforarun can tackle as he's working currently on the virtual_site writer stuff.

[askforarun]

I think yes. I would definitely would. I will speed up the pace.