Generate Select * for queries when applicable for shorter SQL

[smitpatel]

Currently we project all the columns from a table in the projection. We can project SELECT t.* for generate shorter SQL.
Notes to implementer:

• Best place to do would be SQL Gen. Method GenerateProjection. We can detect that all the projection expressions are column expression and coming from same table then we can use table.* directly.
• Overriding method will allow provider to change the "optimization". e.g. postgres does not project "xmin" column out of the table, SELECT * in such cases, need to list all the columns.

[AndriySvyryd]

We do this defensively akin the discriminators. This behavior should be toggleable.

[roji]

Overriding method will allow provider to change the "optimization". e.g. postgres does not project "xmin" column out of the table, SELECT * in such cases, need to list all the columns.

Thanks for remembering PG :) PG can actually also do SELECT xmin, t.* so this is useful even when we need xmin.