Reimplement comparison operator
Reimplement comparison operator

Summary:
Currently the comparison operator relies on the ability to convert to folly::Optional from DeprecatedOptionalField. In order to re-implement DeprecatedOptionalField, we can reimplement all comparison operators first.

(Note: this ignores all push blocking failures!)

Reviewed By: yfeldblum

Differential Revision: D20455512

fbshipit-source-id: 4037251e79ddeb5a3af8a46aa7cfb45944ecd2fc

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