t4216: add end to end tests for git log with Bloom filters

t4216: add end to end tests for git log with Bloom filters

These tests exercises writing commit graph with Bloom filters
and exercises 'git log -- path' with all the applicable
options. They check that the output is the same with and
without Bloom filters, confirm Bloom filters were used by
checking if trace2 statistics were logged correctly.

Also confirms cases where Bloom filters are not used:
1. Multiple path specs,
2. --walk-reflogs (see patch titled 'revision.c: use Bloom filters...'
   for details,
3. If the latest commit graph does not have Bloom filters

Signed-off-by: Garima Singh <garima.singh@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>