base/conversion: setContentType before converting to base format

some conversion (TextDocument) depend on the content type, so it's
necessary to first update the content type before trying to convert to
base format

bt5/erp5_base/WorkflowTemplateItem/portal_workflow/document_conversion_interaction_workflow/interaction_Document_base_convertable.xml

@@ -10,8 +10,9 @@
             <key> <string>categories</string> </key>
             <value>
               <tuple>
-                <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_convertToBaseFormat</string>
+                <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_guessMimeType</string>
                 <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_upload</string>
+                <string>after_script/portal_workflow/document_conversion_interaction_workflow/script_Document_convertToBaseFormat</string>
               </tuple>
             </value>
         </item>

bt5/erp5_base/WorkflowTemplateItem/portal_workflow/document_conversion_interaction_workflow/interaction_Document_file.xml

@@ -22,7 +22,7 @@
         </item>
         <item>
             <key> <string>guard_expression</string> </key>
-            <value> <string>here/hasFilename</string> </value>
+            <value> <string>not: here/isSupportBaseDataConversion</string> </value>
         </item>
         <item>
             <key> <string>guard_group</string> </key>

bt5/erp5_base/WorkflowTemplateItem/portal_workflow/document_conversion_interaction_workflow/script_Document_guessMimeType.py

@@ -2,7 +2,7 @@ document = state_change['object']
 portal = document.getPortalObject()
 
 filename = document.getFilename()
-content_type = portal.mimetypes_registry.lookupExtension(filename)
-
-if content_type is not None:
+if filename:
+  content_type = portal.mimetypes_registry.lookupExtension(filename)
+  if content_type is not None:
     document.setContentType(str(content_type))