Showing index set in stream listing only if user is permitted to.
This PR adds a check for the permission and the presence of the index
set definition in the component showing the stream summary, rendering
index set details only if both are present.
## Motivation and Context
This is fixing an issue where it's implicitly assumed that a user
navigating to the streams page has the required permissions to list all
index sets. This might not be the case for non-admin users, leading to
the streams page breaking completely.
## Types of changes
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)
- [x] My code follows the code style of this project.
- [ ] My change requires a change to the documentation.
- [ ] I have updated the documentation accordingly.
- [ ] I have read the **CONTRIBUTING** document.
- [ ] I have added tests to cover my changes.
- [x] All new and existing tests passed.