DISKSPD should validate that numeric parameters are of expected pattern

[dl2n]

Validate that numeric parameters follow their expected patterns:

[0-9]+(K|M|G|T) for the ones taking sizes
[0-9]+ for the ones taking plain numbers

For example:

-C10G : invalid, since cooldown only takes plan numeric (validate that all char are [0-9])
-r48h : invalid, since h is not a valid character in the size pattern

The reason -C10G is interesting is that its a somewhat common typo/transpose when -c10G was intended. This would error it out.