benchmark

Provide helpers to create integer lists for the given ranges. (#1179)

This can be used together with ArgsProduct() to allow multiple ranges
with different multipliers and mixing dense and sparse ranges.

Example:
BENCHMARK(MyTest)->ArgsProduct({
  CreateRange(0, 1024, /*multi=*/32),
  CreateRange(0, 100, /*multi=*/4),
  CreateDenseRange(0, 4, /*step=*/1)
});

Co-authored-by: Jen-yee Hong <pcmantw@google.com>