Draft: align MolOpt functions with GuacaMol implementation

[AustinT]

My testing showed that MolScore's version of some of the MolOpt (GuacaMol) functions differs from that of the original package. This PR applies some (partial) fixes.

1. Fingerprint size: the original GuacaMol functions use a $2^{32}$ bit (sparse) fingerprints, whereas the implementations in MolScore use a 1024 bit (dense) fingerprint. This causes all similarity values to be slightly overestimated. I increased the fingerprint length to 16384 to reduce the overestimation.
2. Fix Deco hop threshold: the implementation here used a threshold of 0.75, but the paper and code use 0.85.
3. Align some MPO modifiers with GuacaMol's code in instances where paper and code differ. I didn't realize that GuacaMol's official implementation of their functions differs from the paper in several places. In these instances, I think it is better to side with their official code, because this is what prior works have used.
   • Fexofenadine_MPO: the paper specifies an STD of 2 for the TPSA and logP modifies, but the code uses 10 and 1 respectively. This causes scores to generally be a lower in GuacaMol's implementation compared to MolScore.
   • Osimertinib_MPO: sigmas are also different (original code)
4. Fixed SMARTS string in Scaffold hop (in response to Bug in scaffold hop task from PMO benchmark #45 )
5. Fixed bug in isomer similarity calculation: the GuacaMol paper and code specify that the element-wise difference is taken with respect to elements in the target molecule only, while MolScore's implementation uses both the target and query molecules. A simple 1-line change fixes this.
6. Fixed fingerprint lengths in legacy QSAR: JNK3 and GSK3B both use radius 2 fingerprints, not radius 3.

Also, I removed a spurious resource called molscore.configs.MolOpt-DF which does not exist in the repo (maybe it exists for you locally??)

Currently I have this PR marked as a draft. This is because

1. The functions still don't seem to be 100% aligned (I still found small differences in Sitagliptin MPO, Valsartan SMARTS, and scaffold hop)
2. If these fixes are accepted, they should be made in other places in the repo.