OPENDJ-1308 Migrate schema support

In SubstringIndexer.createKeys(), used the IndexingOptions parameter rather than the field.
Caller of createKeys() was passing in a null IndexingOptions, so this has to be fixed all the way up the call hierarchy.



SubstringIndexer.java:
In createKeys(), used the IndexingOptions parameter rather than the field.
In ctor, remove now unused IndexingOptions parameter.


AttributeIndex.java:
Consequence of the change to SubstringIndexer.
Added getIndexingOptions().
In applyConfigurationChange(), also used applyChangeToIndex() for substringIndexer.
In addEntry(), removeEntry() and modifyEntry(), renamed local variables + passed down the IndexingOptions.

Indexer.java, ID2CIndexer.java, ID2SIndexer.java, PresenceIndexer.java:
In indexEntry(), replaceEntry() and modifyEntry(), added IndexingOptions parameter.
Added Indexer.toString() to mutualize javadocs for this method.
Used {@inheritDoc}.

Index.java, NullIndex.java, JEExtensibleIndexer.java:
In a few methods, added IndexingOptions parameter + passed them down.


VerifyJob.java:
In iterateIndex(), passed down the IndexingOptions.
In iterateAttrIndex(), added IndexingOptions parameter + passed them down + removed unused parameters.
Removed now unused IndexType enum.

Importer.java:
In fillIndexKey(), processIndexes() andprocessExtensibleIndexes(),
In a few methods, added IndexingOptions parameter + passed them down.

TestBackendImpl.java:
In newSubstringIndexer(), consequence of the change to SubstringIndexer ctor.
Extracted method getOptions() + called it from assertIndexContainsID() methods.