[BUG] Creating variable or variable group with SAS storage token fails

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

## Describe the bug

**Command Name**
`az pipelines variable-group create
Extension Name: azure-devops. Version: 0.18.0.`

**Errors:**
'ss' is not recognized as an internal or external command,
operable program or batch file.
'srt' is not recognized as an internal or external command,
operable program or batch file.
'sp' is not recognized as an internal or external command,
operable program or batch file.
'se' is not recognized as an internal or external command,
operable program or batch file.
'st' is not recognized as an internal or external command,
operable program or batch file.
'spr' is not recognized as an internal or external command,
operable program or batch file.
'sig' is not recognized as an internal or external command,
operable program or batch file.

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

az pipelines variable-group create --name 'ci-variables' --authorize true --variables ARM_SAS_TOKEN=$ARMSASToken
or
az pipelines variable-group variable create --name ARM_SAS_TOKEN --group-id $groupid --value $ARMSASToken

- _Put any pre-requisite steps here..._
$ARMSASToken = (az keyvault secret show --vault-name $keyvaultname --name 'TF-ARMSASToken' | ConvertFrom-Json).value

## Expected Behavior
Creation of a variable or variable group with an variable in it.

## Environment Summary
```
Windows-10-10.0.19041-SP0
Python 3.6.6
Installer: MSI

azure-cli 2.7.0 *

Extensions:
azure-devops 0.18.0
front-door 1.0.7
interactive 0.4.3

```
## Additional Context
it takes only the first part of the string until it reaches &