Fixes #881
It still takes a bit until diagnostics arrive, but this way error messages from `cargo` are included as well.

See:
- workbenchdev/demos#94
- #879
- #738

Before this change, Workbench installed via Flatpak was not able to run
Vala demos that required Shumate, Libportal or Libspelling because their
header files were removed by the cleanup process. The versions of
Workbench that are run from Builder or flatpak-vscode can actually
compile and execute this demos because they don't do any clean-up, and
therefore none of the header files are deleted, which is probably why
this issue went unnoticed for quite some time even when porting the
affected demos to Vala.

In order to test this changes and compare them with the current version
of Workbench, it is necessary to export a bundle and install it, so the
cleanup process is actually done.

Closes #885

Fixes #828

`libxmljs` one of our nodejs dependencies requires a C++ compiler

Co-authored-by: Sonny Piers <sonny@fastmail.net>
Co-authored-by: Marco Capypara Köpcke <hello@capypara.de>

Co-authored-by: Sonny Piers <sonny@fastmail.net>

This commit adds my name to the contributor list for #857 

Thanks so much for the patience and help I received from you @sonnyp
@theCapypara

workbenchdev/demos#120

We only support English