Add all systems from the opls stress tests

[IAlibay]

Input submission checklist

• created a directory for each system based on the template directory
• named and placed the directory with the following pattern: input_structures/prepared_structures/<set_name>/<system_name>

For each submitted directory:

• filled in system preparation details in the PREPARATION_DETAILS.md file
• added a PDB file with the protein named protein.pdb
• removed any cofactors from the PDB file and placed them in cofactors.sdf
• did not re-protonate the residues, but left protonation state of the protein unchanged
• kept cystallographic waters and metals in the PDB file
• tested the PDB and, if available, cofactors.sdf file using the input validation script
• copied over the ligands SDF file to a file named ligands.sdf and removed any duplicate binding modes or protonation states, keeping the more favorable state

Summary of changes

Licensing agreement

• I agree to release these inputs under the combined MIT and CCBY SA 4.0 licenses of this repository

[IAlibay]

@jthorton this and the cr_bace2 systems are the one where I'm getting a ton of odd Molecule creation failure on Protocol execution. I don't get them when I assign partial charges the first time around, so it might be an openff->rdkit->openff roundtrip thing.

[hannahbaumann]

Could it be that it needs the CHG line to determine which atoms should be charged?
E.g.
M CHG 2 2 -1 8 -1