fix(import): readable dropdowns in dark mode, select all and none

public/i18n/en.json

@@ -654,6 +654,8 @@
     "SAVE": "Add {{count}} games",
     "SAVE_FAILED": "Could not save the import.",
     "NEW": "New import",
+    "SELECT_ALL": "Select all",
+    "SELECT_NONE": "Deselect all",
     "LINE": "Line {{line}}",
     "SEARCH_FAILED": "Search failed",
     "SEARCH_AGAIN": "Search again",