[Feature] Print number of variables when calling leo run

[vicsn]

🚀 Feature

It would be great if we would also print the number of internally generated variables:

• 'helloworld.aleo/main' - 33 constraints and X internal variables (called 1 time)

Motivation

Since introducing AleoNet/snarkVM#2444
Its useful for developers to know how many variables their program is generating.

This will also require adjusting the CallMetrics struct.