az bot directline create doesn't allow multiple sites

**Related command**
```
az bot directline create --name foo --resource-group bar -s Site1
```

**Describe the bug**
The azure cli create option for directline channel (az bot directline create ) just allow one site. In the web portal several can be added and the response object from the az bot directline show is even an array.
Running the command multiple times override the previous one.
The code just take one site as parameter https://github.com/Azure/azure-cli/blob/a89609125772d15a7a39ab2c2a267717c7198d1b/src/azure-cli/azure/cli/command_modules/botservice/channel_operations.py#L123

**To Reproduce**
```
az bot directline create --name foo --resource-group bar -s Site1
```
**Expected behavior**
## Environment Summary
```
macOS-12.5-x86_64-i386-64bit, Darwin 21.6.0
Python 3.10.5
Installer: HOMEBREW

azure-cli 2.38.0 *

Extensions:
aks-preview 0.5.70

Dependencies:
msal 1.18.0b1
azure-mgmt-resource 21.1.0b1
```

Several sites can be used as command parameter:
```
az bot directline create --name foo --resource-group bar -s Site1 Site2
```
Or
```
az bot directline create --name foo --resource-group bar -s Site1 -s Site2
```

**Additional context**
Raised in old repository https://github.com/microsoft/botbuilder-tools/issues/1404