Save multiple workspaces into ASCII

[GuiMacielPereira]

Is your feature request related to a problem? Please describe.

Anna (Vesuvio instrument scientist) reported that when saving multiple files from the ADS, the Save button changes to allow saving only to a nexus file. She reported that it's quite annoying having to save multiple workspaces one by one in ASCII, and suggested that we add the option to save to ASCII when multiple workspaces are selected.

Screeshot form when multiple workspaces are selected (Save button hides ASCII option):

Describe the solution you'd like

Have the save alternative of saving to an ASCII file as the case for a single workspace selected.

Additional context
This is not specific to Vesuvio, so I assume this would improve quality of life for scientists across all instruments.