Make MIME-type icons monochromatic

As part of CMS-8565, Anton created new SVG icons for different mime types in the CMS' assets section. Some of these icons contains text (such as "zip", "odt" etc.) wich is "hardcoded to the color white (a second color on top of the "fill" color). When these icons are displayed for a selected item (blue background, white foreground), these text labels disappear, because they are white, too.

The SVGs should be adjusted such that the text is not using a hard-coded color, but represents a "cut-out" of its surrounding rectangle, such that it is displayed using the background color (blue in case of a selected item).

A screenshot of the problem is attached to CMS-8565. I was able to manually fix a single variant of the ZIP mime-type icon, but fixing all of them without tooling is undoable. I therefore request "improved" icons.