Hidden pk as sequence

Update the internal AIS processing to have tables with no primary key use a hidden column with a sequence. Previous this would use the hidden column with a unique ID generator. The latter has proven to be a performance bottleneck. So simplify the code by removing the unique ID generator and using a sequence instead. 

The challenge here is may pieces of code assumed the hidden column/unique id, and needed to be touched/updated to correct.  The biggest headache here were the Alter Table changes trying to ensure the hidden column, sequence, and PK were correct passed along if unchanged or removed if adding a new PK. 


The `dropTableWithIdentity()` test creates two tables, both with identity column. It verifies that, at the start there are no sequences in the AIS, after creation there are exactly two, and after dropping, there are none again. If the FullTextIndexService is started, it creates one sequence. This makes the verification process on this test both complex and fragile.