Can't do memory-optimized tables with comments

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SqlServer's migrations generator for CreateTable and AddColumn call base and then tacks on WITH (MEMORY_OPTIMIZED = ON). But the base implementation now renders comments as well, which are different statements, so we get mangled SQL.

This makes me question the general model of optionally terminating or not - in Npgsql I never use it, since I typically have to insert SQL in the middle anyway, so I end up duplicating the SQL. There are still some places in SqlServer where terminate false is used without bugs (e.g. AddForeignKey) but I'm not sure it's worth it.

What generally works better IMHO is separating out logic for fragments inside statements, e.g. CreateTableColumn, CreateTableConstraints, GenerateComment.

We can consider removing this, or fix CreateTable and AddColumn specifically.

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/cc @bricelam