OPENDJ-1308 Migrate schema support


Started using SDK's index query factory into OpenDJ server code.
Made common code glaringly evident.
Prepared for more work on this suggest and added TODO's and FIXME's.


IndexQueryFactory.java: REMOVED
Replaced by the SDK class with the same name.

IndexConfig.java: REMOVED
Replaced by SDK's IndexingOptions.

ExtensibleMatchingRule.java:
Consequence of replacing IndexConfig.


ExtensibleIndexer.java:
Now implements Indexer.
Removed getPreferredIndexName(), replaced by getIndexID().
Implemented the empty createKeys().
Pulled up getKeys() + extracted static method computeModifiedKeys() to be able to reuse it.

ApproximateIndexer.java, EqualityIndexer.java, OrderingIndexer.java:
Extracted methods getKeys() + reworked the code a bit to make it all look similar.

SubstringIndexer.java:
Extracted methods getKeys() + reworked the code a bit to make it all look similar.
Replaced int substrLength field with indexingOptions field + Modified ctor + Removed getSubStringLen()

TestBackendImpl.java:
Consequence of the changes to SubstringIndexer.

CollationMatchingRuleFactory.java, TimeBasedMatchingRuleFactory.java:
Consequence of replacing IndexConfig.
Reworked the code a bit to make it all look similar.
Implemented getIndexID() in inner classes.
Pulled up one getKeys() method from inner classes.

JEExtensibleIndexer.java:
Made the code look similar to the other indexers.


AttributeIndex.java:
Used Indexer.getIndexID().
Consequence of replacing IndexConfig.
Changed the code to pass in JEIndexConfig to SubstringIndexer.


IndexQueryFactoryImpl.java:
Consequence of replacing IndexQueryFactory.
Implemented getIndexingOptions() + Added indexingOptions field + modified Ctor.