Support for the C++ Appender API

[willium]

It'd be great to be able to bulk imports from JavaScript in-memory data. DuckDB exposes a C++ Appender API for this purpose, and it's much more performant than INSERT statements.

[willium]

The API is fairly simple (here is the Java wrapper of the C++ class)

[rprovodenko]

Interesting, I'll take a look into this