[FEATURE] add derived stats to --visualize

[5surim]

scarab-infra/scarab_stats/scarab_stats.py

Lines 145 to 146 in fe2b3f5

	def derive_stat(self, equation:str, overwrite:bool=True, pre_agg:bool=True,
	write_prot:bool=False):

is the API to derive a stat by using a given equation as the following.

scarab-infra/scarab_stats/scarab_stats.py

Lines 624 to 628 in fe2b3f5

	# Derive IPC
	experiment.derive_stat("Cumulative_IPC = Cumulative_Instructions / Cumulative_Cycles", write_prot = True)
	print("INFO: Cumulative_IPC calculated.")
	experiment.derive_stat("Periodic_IPC = Periodic_Instructions / Periodic_Cycles", write_prot = True)
	print("INFO: Periodic_IPC calculated.")

In the JSON descriptor, we want to add a functionality to input a derived stat's name and equation and include it in the visualization when running ./sci --visualize <descriptor>.

Please work on top of #246.

xguang119