SERVER-39239 sets up index builds on secondaries to wait for a commitIndexBuild oplog entry before committing an index.

This ticket hooks up abortIndexBuild. The primary's index build should write an abortIndexBuild oplog message whenever it fails. The secondary's index build should not fail prior to the loop added in SERVER-39239 to wait for commitIndexBuild, so we'll add handling for an abortIndexBuild oplog entry there as well.

This is a first basic implementation, so later we'll functionality to react to abortIndexBuild signals at earlier points in the index build.