Summary:
Add methods to set the various functions (Parse, Serialize, Equals) to the OptionTypeInfo.  These methods simplify the number of constructors required for OptionTypeInfo and make the code a little clearer.

Add functions to the OptionTypeInfo for Prepare and Validate.  These methods allow types other than Configurable and Customizable to have Prepare and Validate logic.  These methods could be used by an option to guarantee that its settings were in a range or that a value was initialized.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9411

Reviewed By: pdillinger

Differential Revision: D36174849

Pulled By: mrambacher

fbshipit-source-id: 72517d8c6bab4723788a4c1a9e16590bff870125