Sqlite Migrations: Support HasComment()

[bricelam]

modelBuilder.Entity<MyEntity>().Property(e => e.MyProperty).HasComment("My comment");

...should generate...

CREATE TABLE MyEntity (
    ...

    -- My comment
    MyProperty TEXT,

    ...
);

Users can see the full create statement (including comments) using the following SQL:

SELECT sql
FROM sqlite_master
WHERE name = 'MyEntity';