Startup / wecome dialog blocks CLI processing

Steps to reproduce:

• Run a CLI command like
  inkscape --actions="window-close"

What happened?

Startup dialog pops up.

What should have happened?

Startup dialog must not be shown when processing files from CLI.

Inkscape Version:

• Inkscape Version: Inkscape 1.1-alpha (9ce253cb, 2021-03-14)