CodeGen from PR 15274 in Azure/azure-rest-api-specs

Time Series Insights - add 2021-06-30-preview API version, and supportsCustomerManagedKey output property (#15274)

* Adds base for updating Microsoft.TimeSeriesInsights from version stable/2020-05-15 to version 2021-06-30-preview

* Updates readme

* Updates API version in new specs and examples

* Add supportsCustomerManagedKey to env response definition, examples

Author: SDKAuto