softmaker-office: fix desktop items

Fix desktop items to pass validation:

- Remove icon file extension.
- Remove categories that are not defined by the specification.
- Remove a duplicate MIME type in the PlanMaker desktop file

pkgs/applications/office/softmaker/desktop_items.nix

···
   planmaker = makeDesktopItem {
     name = "${pname}-planmaker";
     desktopName = "${suiteName} PlanMaker";
-    icon = "${pname}-pml.png";
-    categories = "Application;Office;SpreadSheet;";
+    icon = "${pname}-pml";
+    categories = "Office;";
     exec = "${pname}-planmaker %F";
-    mimeType = "application/x-pmd;application/x-pmdx;application/x-pmv;application/excel;application/x-excel;application/x-ms-excel;application/x-msexcel;application/x-sylk;application/x-xls;application/xls;application/vnd.ms-excel;application/vnd.stardivision.calc;application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;application/vnd.openxmlformats-officedocument.spreadsheetml.template;application/vnd.ms-excel.sheet.macroenabled.12;application/vnd.openxmlformats-officedocument.spreadsheetml.template;application/vnd.ms-excel.template.macroEnabled.12;application/x-dif;text/spreadsheet;text/csv;application/x-prn;application/vnd.ms-excel.sheet.binary.macroenabled.12;";
+    mimeType = "application/x-pmd;application/x-pmdx;application/x-pmv;application/excel;application/x-excel;application/x-ms-excel;application/x-msexcel;application/x-sylk;application/x-xls;application/xls;application/vnd.ms-excel;application/vnd.stardivision.calc;application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;application/vnd.openxmlformats-officedocument.spreadsheetml.template;application/vnd.ms-excel.sheet.macroenabled.12;application/vnd.ms-excel.template.macroEnabled.12;application/x-dif;text/spreadsheet;text/csv;application/x-prn;application/vnd.ms-excel.sheet.binary.macroenabled.12;";
     extraEntries = ''
       TryExec=${pname}-planmaker
       StartupWMClass=pm
···
   presentations = makeDesktopItem {
     name = "${pname}-presentations";
     desktopName = "${suiteName} Presentations";
-    icon = "${pname}-prl.png";
-    categories = "Application;Office;Presentation;";
+    icon = "${pname}-prl";
+    categories = "Office;";
     exec = "${pname}-presentations %F";
     mimeType = "application/x-prdx;application/x-prvx;application/x-prsx;application/x-prd;application/x-prv;application/x-prs;application/ppt;application/mspowerpoint;application/vnd.ms-powerpoint;application/vnd.openxmlformats-officedocument.presentationml.presentation;application/vnd.ms-powerpoint.presentation.macroenabled.12;application/vnd.openxmlformats-officedocument.presentationml.template;application/vnd.ms-powerpoint.template.macroEnabled.12;application/vnd.ms-powerpoint.slideshow.macroenabled.12;application/vnd.openxmlformats-officedocument.presentationml.slideshow;";
     extraEntries = ''
···
   textmaker = makeDesktopItem {
     name = "${pname}-textmaker";
     desktopName = "${suiteName} TextMaker";
-    icon = "${pname}-tml.png";
-    categories = "Application;Office;WordProcessor;";
+    icon = "${pname}-tml";
+    categories = "Office;";
     exec = "${pname}-textmaker %F";
     mimeType = "application/x-tmdx;application/x-tmvx;application/x-tmd;application/x-tmv;application/msword;application/vnd.ms-word;application/x-doc;text/rtf;application/rtf;application/vnd.oasis.opendocument.text;application/vnd.oasis.opendocument.text-template;application/vnd.stardivision.writer;application/vnd.sun.xml.writer;application/vnd.sun.xml.writer.template;application/vnd.openxmlformats-officedocument.wordprocessingml.document;application/vnd.ms-word.document.macroenabled.12;application/vnd.openxmlformats-officedocument.wordprocessingml.template;application/vnd.ms-word.template.macroenabled.12;application/x-pocket-word;application/x-dbf;application/msword-template;";
     extraEntries = ''