[FEA] Update benchmark Jenkins job to optionally run benchmarks for prior merge commits

[rlratzel]

Using the new utils (#15) to set up an environment from a prior date based on a specific commit, update the benchmark Jenkins job for cugraph to either run a benchmark using the latest packages and sources (default), or using the latest packages and sources at the time of one or more prior commits.

[rlratzel]

This is now post-MVP