feat(service): add gotify

[catfishlty]

Description

Add gotify service.

Motivation and Context

Implemented #455 and continue closed PR #487 created by @heyztb.
Also thanks to @heyztb for helping me.

How Has This Been Tested?

• Unit test
• Integration tests using real services.

Screenshots / Output (if appropriate):

• The first message has a priority of 10.
• The second message has a priority of 5 (default).

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)
• Other

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.