[Reference] Simulating transactions

[mcintyre94]

The simulate transaction call seems to be really powerful but I'm struggling a lot with finding documentation for making use of it. I think this is probably big enough to be a reference, but might be wrong about that. Some snippets I think we could include:

• Getting the transaction fee
• Calculating the SOL that will be transferred
• Working out any SPL tokens that will be transferred

[jacobcreech]

This may be good as a guide! Something also covering what happens under the hood for simulate, as well as how to use for debugging(getting logs). Some snippets like suggested would also be good. Note that there is a new getEstimatedFee method on transaction though