Proof that CreateIndexBuilder.NonClustered() does not affect index creation statement on SQL Server.

CreateIndexBuilder_SqlServer_NonClustered_CreatesNonClusteredIndex() fails expecting NONCLUSTERED but getting CLUSTERED.
CreateIndexBuilder_SqlServer_Unique_CreatesUniqueNonClusteredIndex() fails expecting UNIQUE NONCLUSTERED but getting CLUSTERED.
Made CreateIndexBuilder set IndexType in Clustered(), NonClustered() and Unique().
Merge pull request #248 from lars-erik/6.2.0-fix-sqlsyntaxprovider-indexclustring

6.2.0 fix sqlsyntaxprovider indexclustring