Draw contents from a byte string instead of generating arbitrary hashes
This generates more realistic contents and avoids spurious HashCollisions when generating a set of objects using these hypothesis strategies, at the cost of slightly worse "boundary checking" (i.e. we won't check contents with a length > 4096 bytes).
Depends on !86 (closed).
Test Plan
tox tests still pass
Migrated from D2739 (view on Phabricator)