OPENDJ-1308 Migrate schema support

Added one test for CollationMatchingRuleFactory.
In CollationMatchingRuleFactory.matchSubstring(), could remove call to subIndexer.getSubstringLength() which triggered removing now useless IndexingOptions parameter in ExtensibleMatchingRule.getIndexers().



JEExtensibleIndexer.java:
In ctor, removed useless MatchingRule parameter.

ExtensibleMatchingRule.java:
Removed useless IndexingOptions parameter from getIndexers().

CollationMatchingRuleFactory.java:
Consequence of the change to ExtensibleMatchingRule.getIndexers().
In getIndexers(), simplified the code.
In matchSubstring(), used the factory parameter rather than calling subIndexer.getSubstringLength().
In CollationSubstringExtensibleIndexer(), removed now unused substringLen field + removed getter/setter + removed ctor parameter.
Code formatting.

TimeBasedMatchingRuleFactory.java:
Consequence of the change to ExtensibleMatchingRule.getIndexers().

AttributeIndex.java:
Consequence of the change to ExtensibleMatchingRule.getIndexers().
Extracted new methods newIndex(), newExtensibleIndex(), openIndex().
Changed openNewIndex() method.
In listDatabases(), used List.addAll().
In applyConfigurationChange(), used Set.removeAll().
In getRules(), reused local variables + reverted if statement.
Code formatting and some cleanup (Removed useless assignments).



TestBackendImpl.java
Consequence of the change to JEExtensibleIndexer.


CollationMatchingRuleFactoryTest.java: ADDED

TimeBasedMatchingRuleFactoryTest.java:
Removed unnecessary dependency to CollationMatchingRuleCfg.