DevTestCenter CLI

**Resource Provider**
Dev Test Center

**Description of Feature or Work Requested**
We are creating an Azure PowerShell CLI for a new service, DevTestCenter. DevTestCenter is a service that allows corporate IT departments to set policy for how their development teams create CI/CD resources hosted in Azure.

**Minimum API Version Required**
Dunno.

**Swagger Link**
[devtestcenter.json](https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdevdiv.visualstudio.com%2FOnlineServices%2F_git%2Fazure-devtest-center%3Fpath%3D%252Fsrc%252Fsdk%252Fspecification%252Fdevtestcenter%252Fresource-manager%252FMicrosoft.DevTestCenter%252Fpreview%252F2021-01-01-alpha%252Fdevtestcenter.json&data=04%7C01%7Cchrkin%40microsoft.com%7C24db723ccffd49310fe308d8c2350089%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637472880180684958%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=BMWndVjvTLdQHjWhode6mZ8doKVn4%2BZDuHyzcaSwSEI%3D&reserved=0)

**Target Date**
Private Preview Date: 2021-04-30