default Filename + extension should be set

Summary:

There is no default filename and extension assigned to a file in Save Dialog Forms while New Document / File is chosed, for which the WMF format will be saved to the file and while the file is opened the format will not be recognized, but only the .wmf extension is provided to the filename.

Steps to reproduce:

• open Inkscape
• select New Document
• do what ever the changes you want to the document. The following are affected in the same way:
• File/Save Or
• File/Save as... Or
• File/Save a Copy...

What happened?

While the above Save Dialog Forms are open there is no default filename + extension. If I type the file name without any extension, and on the right bottom "Guess from extension" is selected as default, the default format the file will be saved is WMF.

What should have happened?

It should be assumed to have .svg extension already selected on the bottom right if this is the default inkscape extension. If the user want to change it then so be it. Otherwise it will save the user a lot of time investigating why the file can't be open even if the WMF format is defaulted(in this case). While opening the file, the format will not be recognized and an error message will be popped out: "Could not detect file format. Tried to open it as an SVG, but this also failed" If the file format is assumed only from extension and the only format tried to SVG, then this should be extended to all supported formats.

Version info

Strange the reported version in GUI is 1.3.2...

> inkscape --debug-info

Inkscape 1.3.1 (9b9bdc1480, 2023-11-25, custom) 

    GLib version:     2.72.4
    GTK version:      3.24.33
    glibmm version:   2.66.2
    gtkmm version:    3.24.5
    libxml2 version:  2.9.13
    libxslt version:  1.1.34
    Cairo version:    1.16.0
    Pango version:    1.50.6
    HarfBuzz version: 2.7.4

    OS version:       Ubuntu Core 22