Allow Grafana resource provisioning via AWS

[andyRokit]

As a DevOps engineer I want to be able to configure AMG with data sources, dashboards, alerts etc. via AWS (console, CLI, CloudFormation and CDK) So that I can fully automated my deployments

In terms of implementation, I would imagine that this may be as simple as providing YAML inputs on the AGM console (and others).

E.g.

1. [Amazon Grafana > Workspaces > my-managed-grafana]
2. [Provisioning] (new tab)
3. [Add Datasource] adds a new YAML textbox
4. Paste and save datasouce config [1] into textbox
5. AWS pushes new YAML file(s) to Grafana instance and restarts the service

[arun-annamalai]

Second this, I would add on that support via CFN/CDK would be the most preferred way