ERP5: generate an interpreter for theia

Set in preferences the path of this interpreter, for example:

```json
{
  "python.pythonPath": "/srv/slapgrid/slappart19/srv/runner/software/91be79296dea036ad98d4aff08ecb74b/bin/python"
}
```

then when editing products files completions and jump to definition should work. It works but it is sometimes so slow that it seems not working.

See merge request nexedi/slapos!1153