CodeGen from PR 15845 in Azure/azure-rest-api-specs

[Hub Generated] Review request for Microsoft.Insights to add version stable/2021-08-01 (#15845)

* Adds base for updating Microsoft.Insights from version preview/2021-02-01-preview to version 2021-08-01

* Updates readme

* Updates API version in new specs and examples

* Added new stable api version 2021-08-01 with paging support

Co-authored-by: Avi Jerafi <[email protected]>

Author: SDKAuto