Measure static guard nodes with OnionPerf

The specifications for measuring this are as follows:

OP should measure one guard or set of guards at a time. It could use NumEntryGuards in the torrc file to support more than 1 guard
A new guard/set of guards must be chosen after a day of measurement
All CBT data must be erased when choosing a new set of guards, after day of measurements (at UTC midnight). This could mean erasing or replacing the state file for CBT.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information