Improve video folder & group titles

Description

This just add a visual hint of where we are when using grouping on video list/grid view, by adding '/' to the title when inside a folder, or '...' when inside a group.

Motivation and Context

UI improvement

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Enhancement (non-breaking change which cleans up / improves existing functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the CONTRIBUTING section of the README document.