rtmp-services: Add sheeta

[KOUCHANGdw]

Description

add a streaming service "sheeta" into "plugins/rtmp-services/data/services.json"

Motivation and Context

Our service requires broadcasters to set the keyframe interval appropriately to achieve low-latency delivery.

"sheeta" is a service described at the following link: https://www.sheeta-info.com/.
It is a fan club management service that utilizes OBS for its broadcasting features.

How Has This Been Tested?

I did "Local testing" as described in Service Submission Guidelines.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.