Add support for multi stream ingestion via XML and API
1. Support multi stream ingestion via MXL
2. Support multi stream entries creation via the API
3. All access control, entitlement, scheduling, publishing will be
verified on the parent entry if one exists.
Add some comments to the code
Update XSD documentation line
Merge pull request #1891 from kaltura/IX-9.19.8-LCGA

Add support for multi stream ingestion via XML and API