feat: add Centrifugo notification service with usage examples and tests

[srikary12]

Description

Adds Centrifugo notification service

Motivation and Context

Adds support to notify centrifugo service
#944

How Has This Been Tested?

make test
make fmt
make lint

Modifies webpush to pass test case

Screenshots / Output (if appropriate):

Types of changes

• 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)
• Documentation (no code change)
• Refactor (refactoring production code)
• Fixes webpush test case

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[srikary12]

The runner is receiving shutdown signal for lint. Am I missing something here?