[libc++] Refactor the sequence container benchmarks

Rewrite the sequence container benchmarks to only rely on the actual
operations specified in SequenceContainer requirements and add benchmarks
for std::list, which is also considered a sequence container.

One of the major goals of this refactoring is also to make these
container benchmarks run faster so that they can be run more frequently.
The existing benchmarks have the significant problem that they take so
long to run that they must basically be run overnight. This patch reduces
the size of inputs such that the rewritten benchmarks each take at most a
minute to run.

This patch doesn't touch the string benchmarks, which were not using
the generic container benchmark functions previously.

Author: ldionne