Add counter for the number of raw banks and make the reserved number configurable

As noted in !2270 (merged), the expected number of raw banks was hardcoded to a value that was too small.

This makes the value configurable and increases the default to be large enough for current samples.

I also added a counter to help us notice if/when we have different/more realistic samples where the number of banks is not exactly 1025..

Reference update in Moore!368 (merged)