Autocomplete not working with arsd-simpledisplay

[helikopterodaktyl]

Reproduces both with latest available from VSCode marketplace and with v0.23.2 (latest release on github).

Repro steps:

1. Create a new dub project (dub init)
2. Put arsd-official:simpledisplay in list of packages (or run dub add arsd-official:simpledisplay )
3. Open newly created project in VSCode
4. Put some hello world style code, such as: `import arsd.simpledisplay;

void main() { SimpleWindow window = new SimpleWindow(Size(500, 500), "Event example - simpledisplay.d"); } ` 5. Try to autocomplete methods of window variable, doesn't work, VSCode shows generic list of all names in the project.

[bagomot]

This does not work with any arsd-official package. And with some others too, like requests. I tried to understand why, but did not understand.

[WebFreak001]

the issue is that those packages use sourceFiles, which are not supported right now by serve-d (there were some memory issues before when they were supported, but those might have been other bugs as well)

The fix should be quite simple, by passing the sourceFiles into DCD (the PR to support that has been in for a few years already)