Description of problem:
Add possibility to create incremental version with new file.

Currently is possible to create incremental version with errata, rpm, puppet module maybe more, but it is not possible to do incremental-version with file

Version-Release number of selected component (if applicable):
6.8.6
6.9.6.1

How reproducible:
Always

Steps to Reproduce:
1. Create product
2. Create repository type file
3. Upload 1 files to repository
4. Create content view and assign file repository
5. Publish CV version 1.0
6. Wants to create CV in version 1.1 with 1 new file

Actual results:
It is currently not possible.

Expected results:
Add option to create incremental version with file

1. hammer content-view version incremental-update --file-id xx ----content-view-version-id yy

Additional info: