flag for test value range

[pointbazaar]

when running the test, be able to specify how many values to test

we have lots of loops which start at some value, then iterate until start_value + range
where range is pragmatically low to make the test run faster.

But to achieve more coverage, the range of values tested has to be greater.

So every test should accept an uint64_t value_range which tells it how great the range can be at most.

so we can run

./sd-tests --range 50

for example, which would run each test with 50 different values (if the test supports that)