Improve the trace verifier to start from an arbitrary slot

[javierdiaz72]

Why

In #593, we translate Cardano Tracer files into Leios trace verifier files. Such files can start with an arbitrary slot, which is not currently supported by the trace verifier.

What

We need to improve the Leios trace verifier to support trace files that start with an arbitrary slot (i.e., different from 0).

How

We shall add an optional command-line argument starting-slot to the Leios trace verifier in order to supply the starting slot of the trace file (which will be 0 by default).

Internally, the trace verifier will call the verifyTraceFromSlot function instead of the verifyTrace function.