Add support for ad-hoc table renaming

[lukaseder]

Being able to scope schema and table renaming for a whole Configuration through Settings is nice for multi-tenancy but not for sharding. Users who are sharding their tables should be able to rename the "base table" on the fly for ad-hoc usage. Example:

SELECT * FROM t1 -- t1 is renamed from t
UNION
SELECT * FROM t2 -- t2 is renamed from t

In the above example, the table T is renamed twice in the same query, once to T1, and once to T2.

Note that in this context, renaming is not the same as aliasing! Renaming is only performed in Java memory prior to rendering SQL, whereas aliasing is performed in the SQL statement itself.

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As table renaming is not really a SQL DSL feature, the rename() method should be generated onto generated tables only, instead of being declared in org.jooq.Table