Summary:
This patch introduces OptionsSanityCheckLevel internally to enable
sanity check rocksdb options.

Utilities API will be added in the follow-up diffs.

Test Plan: Added more tests in options_test

Reviewers: igor, IslamAbdelRahman, sdong, anthony

Reviewed By: anthony

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D49515