ui: set file name for spice console download in chrome

ui: set file name for spice console download in chrome

When the virt-viewer file is downloaded we already set a file name in
Android, so the file type may be recognized. Also doing this in
Chrome (and Chromium based browsers) allows users to "alyways open
files of this type". So the browser automatically opens the console
window without user interaction.

Signed-off-by: Lorenz Stechauner <l.stechauner@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>