containerapp revision copy --from-revision does not work, always takes latest revision

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

## Describe the bug

Trying to create new revisions based on old revisions. Even when --from-revison parameter is passed, all container env variables are taken from latest revision, same as just using containerapp update command.

**Command Name**
`az containerapp revision copy
Extension Name: containerapp. Version: 0.3.20.`

**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 containerapp revision copy -o {} --from-revision {} -n {} -g {} --set-env-vars {} --revision-suffix {}`

## Expected Behavior
environemnt variables are taken from revision which is specified via --from-revision option

## Environment Summary
```
Linux-5.15.79.1-microsoft-standard-WSL2-x86_64-with-glibc2.34, CentOS Stream 9
Python 3.9.16
Installer: RPM

azure-cli 2.44.1

Extensions:
containerapp 0.3.20

Dependencies:
msal 1.20.0
azure-mgmt-resource 21.1.0b1
```
## Additional Context