Summary:
This change adds File IO Notifications to the SequentialFileReader The SequentialFileReader is extended
with a listener parameter.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8982

Test Plan:
A new test EventListenerTest::OnWALOperationTest has been added. The
test verifies that during restore the sequential file reader is called
and the notifications are fired.

Reviewed By: riversand963

Differential Revision: D31320844

Pulled By: shrfb

fbshipit-source-id: 040b24da7c010d7c14ebb5c6460fae9a19b8c168