[Direct Transfer] Let the user select the document type

As it is done in the Web UI document creation dialog, we should propose the list of possible document types for the current selected remote path. Fortunately this is easy to retrieve using the subtypes adapter.
So types will be dependent of the current selected remote path and the list must be refreshed when it is changed.

And as the remote path is saved in the database, we should keep the document type in it too for next Direct Transfers. This will save us a HTTP call.

This is a snippet of a document subtypes:

<Document changeToken='1-0', contextParameters={
    'subtypes': [
        {'type': 'DocumentRouteInstancesRoot', 'facets': ['SystemDocument', 'Folderish', 'NXTag', 'HiddenInNavigation', 'HiddenInCreation']}, 
        {'type': 'TemplateRoot', 'facets': ['Folderish', 'NXTag', 'SuperSpace', 'HiddenInCreation', 'NotCollectionMember']}, 
        {'type': 'SectionRoot', 'facets': ['Folderish', 'NXTag', 'SuperSpace', 'HiddenInCreation', 'NotCollectionMember', 'MasterPublishSpace']}, 
        {'type': 'CommentRoot', 'facets': ['Folderish', 'NXTag', 'HiddenInNavigation', 'HiddenInCreation']}, 
        {'type': 'WorkspaceRoot', 'facets': ['Folderish', 'NXTag', 'SuperSpace', 'HiddenInCreation', 'NotCollectionMember']}
    ]
}>

Here, we can see interesting facets like HiddenInCreation and so Direct Transfer must respect it. 

Questions

At the end of this Epic, we want to be able to upload a whole hierarchy of folders/files and set the types for all files that will be uploaded AND all folder that will be uploaded (with two new options).

Are the available types for files defined by the selected type for folderish documents?

If this is the case, how do we fetch the available files types for a specified folder type?

Is it possible for a Folderish type to contain folders of the same type? How do we check for this?

The code snippet in the Epic seems to need the folder to be already created to works.