This change adds microbenchmarks for various change streams pipelines.
The benchmarks measure the runtime of change stream event generation via typical regular change stream pipelines.
Measurements are reported for collection-level, database-level and cluster-level change stream pipelines.

The pipelines are generated as they are on replica sets, however, the oplog data source is simulated in the benchmarks in order to not have a lengthy setup phase and disk activity. Thus benchmarks resemble a change stream workload that is 100% CPU-bound.
Currently only CRUD `i` (insert) oplog entries are simulated, but other oplog entry types can be added in the future.

The following stages / change stream flags are currently benchmarked:

• `$match`, with 10%, 25%, 50% and 100% match rates
• `$project` with inclusion and exclusion projections
• `$changeStreamSplitLargeEvent`
• `showExpandedEvents`