Fix playlist preview in the editor

[Rahmon]

Description of the Change

When the user adds a playlist in the editor, the playlist is rendered using a video player. This change fixes the playlist preview to use a playlist player.

Alternate Designs

Benefits

Possible Drawbacks

Verification Process

1. Add the Brightcove block and add a playlist
2. Check if the player utilized is a playlist player

Checklist:

• I have read the CONTRIBUTING document.
• 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 added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

Changelog Entry

Fixed playlist preview in the editor

[oscarssanchez]

Looks good! @Rahmon