drawReaction() should not hit a PRECONDITION with prepareMolsBeforeDrawing=false

[ptosco]

Describe the bug
When MolDrawOptions.prepareMolsBeforeDrawing is set to false the code hits a PRECONDITION.
The problem arises when DrawMol::getAtomSymbol() calls Atom::getTotalNumHs() as implicit valence has not been computed yet.
The fix is simple: it is sufficient to move mol.updatePropertyCache(false) out of the if (drawOptions().prepareMolsBeforeDrawing) {} clause in MolDraw2D::makeReactionDrawMol()`.

To Reproduce

from rdkit import Chem
from rdkit.Chem import rdChemReactions
from rdkit.Chem.Draw import rdMolDraw2D, IPythonConsole

rxn = rdChemReactions.ReactionFromSmarts('[CH3:1]-[OH:2]>>[CH2:1]=[OH0:2]')
d2d = rdMolDraw2D.MolDraw2DSVG(800, 300)
d2d.drawOptions().prepareMolsBeforeDrawing = False
d2d.DrawReaction(rxn)
[09:39:33] 

****
Pre-condition Violation
getNumImplicitHs() called without preceding call to calcImplicitValence()
Violation occurred on line 297 in file /scratch/toscopa1/src/rdkit/Code/GraphMol/Atom.cpp
Failed Expression: d_implicitValence > -1
****

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
/tmp/ipykernel_242993/2731136680.py in <module>
      2 d2d = rdMolDraw2D.MolDraw2DSVG(800, 300)
      3 d2d.drawOptions().prepareMolsBeforeDrawing = False
----> 4 d2d.DrawReaction(rxn)
      5 #d2d.FinishDrawing()
      6 #svg = d2d.GetDrawingText()

RuntimeError: Pre-condition Violation
	getNumImplicitHs() called without preceding call to calcImplicitValence()
	Violation occurred on line 297 in file Code/GraphMol/Atom.cpp
	Failed Expression: d_implicitValence > -1
	RDKIT: 2022.09.1pre
	BOOST: 1_74

Expected behavior
drawReaction() should not fail because a PRECONDITION is hit.