Support replacement scans

[alexeyzimarev]

Replacement scans allow table functions to be used easier, and the API doesn't seem to complex (although a bit hard to understand). It'd be cool to get replacement scans to be supported by Duck.Net.

[Giorgi]

I had a look at the API and replacement scans look like a slimmed version of table functions. According to the documentation The replacement scan can then insert a table function so you would still need to register a custom table function if you want to use that function in a replacement scan.

[alexeyzimarev]

Yeah, exactly. I already have a table function, it works great. Now I am planning for the function to "pretend" that it's a table.

[RusselWebber]

This functionality would be useful for the xlDuckDb project RusselWebber/xlDuckDb#3