Update to Open API specs 2020-09-07

[mikhailshilkov]

Breaking changes:

• This PR pushed a new version of Microsoft.Devices/2020-03-01 to the deviceprovisioningservices folder. However, there is an existing version of Microsoft.Devices/2020-03-01 in the iothub folder and their definitions overlap. In particular, CertificateProperties has no certificate property in the former but does have it in the latter. This caused us to remove the property from our SDK.

• Machine learning services removed several resource properties from PrivateEndpointConnection in this PR:

  They are not a breaking change to our python sdk(currently we only support python sdk). It's more like a correction. Because the PrivateEndpointConnection never supports Identity, Sku all that stuff in our services, so when I try to autorest with the current swagger, I found the issue therefore made this change. Hope it explains better the motivation of the breaking change