--extra-readers option doesn't work if there were previous conversions?

[melissalinkert]

Initial report and test data is on a private thread, which this is mentioned on.

Test steps (on Windows, with 1.0.3):

1. open NGFF-Converter
2. set Convert to to OME-TIFF
3. leave Extra Arguments empty
4. add test input file, leave output file as default
5. click Run Conversions
6. conversion should finish almost instantly
7. add --extra-readers to Extra Arguments box
8. add test input file again, set output file to some other name so both OME-TIFF files are kept
9. click Run Conversions
10. conversion will again finish almost instantly
11. close and reopen NGFF-Converter
12. set Convert to to OME-TIFF
13. add --extra-readers to Extra Arguments box
14. add test input file, set output file to a third unique name (so all 3 OME-TIFF files are kept)
15. click Run Conversions
16. conversion should take much longer
17. inspecting the in-progress .zarr or OME-TIFF after the fact should show lots of data, where the OME-TIFFs from the first 2 steps are very small

Logs suggest that the --extra-readers flag is passed to bioformats2raw in step 9 (as expected), but for some reason it's not being respected. I kind of suspect glencoesoftware/bioformats2raw#145 might be the root cause here, but don't have concrete proof. Bumping to bioformats2raw 0.5.0 would be the first thing to test.