Missing time_slice type handler for the SLO metrics.

[8tomat8]

Note:
If you have a feature request, you should contact support so the request can be properly tracked.

Is your feature request related to a problem? Please describe.
The Create SLO Object endpoint supports type time_slice. But the type is not implemented in the handler and CF resource definition.

Describe the solution you'd like
"type": "time_slice" and sli_specification must be added to the handler, so it can be exposed in the CF resource definition.

Describe alternatives you've considered
Creation of time slice based SLOs using CDK and CF, instead of doing it manually on UI.

Additional context
Add any other context or screenshots about the feature request here.

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