benchmark: add and organize buffer tests

Benchmarks have been created for all Buffer methods. They have also been
placed into benchmark/buffer. The single Typed Array test has been moved
to benchmark/typedarray.
benchmark: add and organize net tests

Benchmarks for the net module have been added or moved to the
benchmark/net directory.

Add call to external _net_callbacks to DRY out complete and interval
calls. This will also be helpful creating cli params to determine output
format.
benchmark: update make bench with new tests

Have updated `make bench` with current tests. When run will output a
simple table with each test's results.