[Module Proposal]: `avm/res/dashboard/grafana`

### Check for previous/existing GitHub issues/module proposals

- [X] I have checked for previous/existing GitHub issues/module proposals.

### Check this module doesn't already exist in the module indexes

- [X] I have checked for that this module doesn't already exist in the module indexes; or I'm proposing the module to be migrated from CARML/TFVM.

### Bicep or Terraform?

Bicep

### Module Classification?

Resource Module

### Module Name

avm/res/dashboard/grafana

### Module Details

The intent of the module is to focus specifically on the Azure Managed Grafana it will support features like private endpoint and management of Grafana configurations.

Note: this will migration of https://github.com/Azure/bicep-registry-modules/tree/main/modules/observability/grafana

[Update] - Here's the latest version published: https://github.com/Azure/bicep-registry-modules/tree/observability/grafana/1.0.3/modules/observability/grafana

### Do you want to be the owner of this module?

Yes

### Module Owner's GitHub Username (handle)

vlahane

### (Optional) Secondary Module Owner's GitHub Username (handle)

_No response_