simulateTransaction RPC endpoint should optionally return program log output

[mvines]

Currently the only way to view log output from programs is by running a validator node and looking for program logging amongst the rest of the validator logs. This is pretty unfriendly.

As an alternative, the simulateTransaction RPC endpoint could setup the environment to capture and return program logging. (one day this could be the path for debugger as well, but that's out of scope for this issue).