Add tests for the theme and icons files

tests/files/all_icons.json

@@ -0,0 +1,114 @@
+[
+    "alert_error",
+    "alert_info",
+    "alert_question",
+    "alert_warn",
+
+    "cls_archive",
+    "cls_character",
+    "cls_custom",
+    "cls_entity",
+    "cls_none",
+    "cls_novel",
+    "cls_object",
+    "cls_plot",
+    "cls_template",
+    "cls_timeline",
+    "cls_trash",
+    "cls_world",
+
+    "prj_folder",
+    "prj_document",
+    "prj_title",
+    "prj_chapter",
+    "prj_scene",
+    "prj_note",
+
+    "fmt_bold",
+    "fmt_italic",
+    "fmt_mark",
+    "fmt_strike",
+    "fmt_subscript",
+    "fmt_superscript",
+    "fmt_underline",
+    "fmt_toolbar",
+
+    "search",
+    "search_cancel",
+    "search_case",
+    "search_loop",
+    "search_preserve",
+    "search_project",
+    "search_regex",
+    "search_replace",
+    "search_word",
+
+    "bullet-off",
+    "bullet-on",
+    "unfold-hide",
+    "unfold-show",
+
+    "sb_build",
+    "sb_details",
+    "sb_novel",
+    "sb_outline",
+    "sb_project",
+    "sb_search",
+    "sb_stats",
+
+    "theme_light",
+    "theme_dark",
+    "theme_auto",
+
+    "add",
+    "bookmarks",
+    "browse",
+    "build_settings",
+    "cancel",
+    "checked",
+    "chevron_down",
+    "chevron_left",
+    "chevron_right",
+    "chevron_up",
+    "close",
+    "copy",
+    "document_add",
+    "document",
+    "edit",
+    "exclude",
+    "export",
+    "filter",
+    "fit_height",
+    "fit_width",
+    "folder",
+    "font",
+    "import",
+    "language",
+    "lines",
+    "list",
+    "margin_bottom",
+    "margin_left",
+    "margin_right",
+    "margin_top",
+    "maximise",
+    "minimise",
+    "more_arrow",
+    "more_vertical",
+    "noncheckable",
+    "open",
+    "panel",
+    "pin",
+    "project_copy",
+    "quote",
+    "refresh",
+    "remove",
+    "revert",
+    "settings",
+    "star",
+    "stats",
+    "text",
+    "timer_off",
+    "timer",
+    "unchecked",
+    "view"
+]