feat(alertmanager): add alertmanagertypes

[grandwizard28]

Summary

add alertmanagertypes

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Important

Add alert manager types and enhance error handling with structured codes, updating related tests and HTTP rendering.

• Alert Manager Types:
  • Add alertmanagertypes package with alert.go, channel.go, config.go, marker.go, receiver.go, and state.go.
  • Implement functions for creating, updating, and deleting alert manager configurations and channels.
  • Add tests for alert manager configurations and channels in channel_test.go.
• Error Handling:
  • Introduce code type in pkg/errors/code.go for structured error codes.
  • Modify errors.go to use code type for error codes.
  • Update tests in errors_test.go to reflect changes in error handling.
• HTTP Rendering:
  • Update render.go to use code type for error codes in HTTP responses.
  • Adjust tests in render_test.go to match new error handling.
• Miscellaneous:
  • Remove NotificationChannel from dashboard.go as it's now handled in alertmanagertypes.

^{This description was created by for ba5746e. It will automatically update as commits are pushed.}