Add filters 'file type' and 'file exist' for resources

[martha-thomae]

I would be useful to filter out the resources in a workflow run by the categories:

• file type
• file exist

When you have so many resources, like when you processed a complete manuscript with hundreds of folios with an end2end OMR workflow, lots of resources have the same name, but their file type is different (see screenshot). Using the "name" filter is not useful in this case, a "file type" filter would be useful to retrieve (let's say) the MEI files generated for all the folios. "File exist" is useful to see which resources weren't generated (to detect if something is wrong).

[martha-thomae]

The filtering by file type might not be necessary if filtering by label was working properly, see issue DDMAL/Rodan#555