Support `az containerapp stop` and `az containerapp start`

**Related command**
`az containerapp`

**Is your feature request related to a problem? Please describe.**
Azure Container Apps REST API supports [stopping](https://learn.microsoft.com/en-us/rest/api/containerapps/stable/container-apps/stop?tabs=HTTP) and [starting](https://learn.microsoft.com/en-us/rest/api/containerapps/stable/container-apps/start?tabs=HTTP) container apps. This same capability should be supported through Azure CLI.

**Describe the solution you'd like**
Add support for `az containerapp stop` and `az containerapp start` mapping to the REST API.

**Describe alternatives you've considered**
Use the REST API directly `az rest -m post -u "/subscriptions/.../resourceGroups/.../providers/Microsoft.App/containerapps/.../stop?api-version=2023-05-01"`.