fileitemaction: use all/all mimetype for plugin discovery

The plugin was restricted to application/octet-stream, so it never
loaded for directories (inode/directory). Now matches all types and
filters internally via actions().

fileitemaction/denote_fileitemaction.json

@@ -1,8 +1,8 @@
 {
     "KPlugin": {
-        "Name": "Denote Rename Action",
-        "Description": "Rename files to conform to denote naming convention",
-        "MimeTypes": ["application/octet-stream"],
+        "Name": "Denote File Actions",
+        "Description": "Create and rename files using denote naming convention",
+        "MimeTypes": ["all/all"],
         "ServiceTypes": ["KFileItemAction/Plugin"]
     }
 }