[#2665] [#2667] [#2676] First API and implementation draft

* [#2665] Implement SPI for RenderContext and BindContext listening to
allow for custom SQL transformation
* [#2667] Add org.jooq.Clause and let org.jooq.Context listen on
start(Clause) and end(Clause) events - First API and implementation
draft
* [#2676] Add QueryPartInternal.clause() to allow for QueryParts to
return Clause information to org.jooq.Context