request for csv delimiter on output of az command

### **This is autogenerated. Please review and update as needed.**

## Describe the bug

**Command Name**
`az extension list-available`

tsv seems to be the only output that is delimited. would like to see a comma separated value output as well. thanks.

**Errors:**
```

```

## To Reproduce:
Steps to reproduce the behavior. Note that argument values have been redacted, as they may contain sensitive information.

- _Put any pre-requisite steps here..._
- `az extension list-available --output {}`

## Expected Behavior

## Environment Summary
```
Linux-5.11.21-100.fc32.x86_64-x86_64-with-glibc2.2.5
Python 3.8.10
Installer: RPM

azure-cli 2.25.0

Extensions:
ssh 0.1.5

```
## Additional Context