All default document templates have user units defined as millimeters (scale wrong)

Summary:

All default document templates including ones with page sizes defined in other units have viewboxes with user units defined as millimeters.

Steps to reproduce:

• in the welcome dialog pick a template with document dimensions defined in pixels or inches
• access Document properties and check the scale (viewbox) settings

What happened?

All document templates have user units defined as millimeters.

What should have happened?

Each document should start with a scale of 1 and the user units matching the units defining document dimensions.

This makes documents easier to read in plaintext and is particularly useful for web applications where human-readable SVG code might be important. I'm not sure if that millimeter user unit is intended or if it carried over because the templates were built starting with a file in millimeters and nobody bothered to change that.

Version info

Inkscape 1.1 (c68e22c387, 2021-05-23)

    GLib version:     2.68.2
    GTK version:      3.24.29
    glibmm version:   2.66.0
    gtkmm version:    3.24.3
    libxml2 version:  2.9.12
    libxslt version:  1.1.34
    Cairo version:    1.17.4
    Pango version:    1.48.5
    HarfBuzz version: 2.8.1
    Poppler version:  20.12.1

    OS version:       Windows 10 2009