[Module Proposal]: `avm-res-containerservice-fleet` (tf)

### 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.

### Bicep or Terraform?

Terraform

### Module Classification?

Resource Module

### Module Name

avm-res-containerservice-fleets

### Module Details

This is a module to create azure container service fleets.
https://learn.microsoft.com/en-us/azure/templates/microsoft.containerservice/fleets?pivots=deployment-language-terraform

cc @amruta53

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

Yes

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

didayal-msft

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

amruta53