The constants in the enum should be named based on the coding conventions

[phillipstanleymarbell]

The constants in the enum should be named based on the coding conventions (e.g., kSunflowerInstructionLatencyIndexIF) to make their use left confusing, since the pipeline structure (P) also has fields called IF, ID, etc.)

https://github.com/physical-computation/sunflower-simulator/blob/e414503efde31eeec176b375a8522353f14d2165/sim/mextern.h#L46