Convergence Diagnostics Related Improvements

[AdityaSavara]

• Make the ACT graphs have x axes that correspond to total samples
o To do so, the plotting function should have an optional argument for "perTotal" or "perChain" regarding how the x axis will be shown.
To get convert the x axis to perTotal, one would multiply a specific point's sample index by the number of chains (since the values are initially in 'perChain').