Max Gabrielsson

After this we only need support for compressed execution (e.g. constant/flat/dict-vectors) in scalar functions to start moving over some more complex extensions to the C-API. (e.g half of spatial).

This PR refactors the `PhysicalCreateARTIndex` into a generic `PhysicalCreateIndex` operator, that uses a new "index build" interface provided by a `IndexType` to construct an arbitrary index. The idea is to...