Using Azure.Storage.Blobs for storage access

[agr]

Progress on https://github.com/NuGet/Engineering/issues/5335

Built on top of https://github.com/NuGet/NuGetGallery/pull/9981 (draft PR), so all the SDK isolation work done there is present here.

Some choices made:

• MaximumExecutionTime support that existed in WindowsAzure.Storage is dropped. Consumers would have to produce cancellation tokens with time limits if needed;
• There are no longer ambient request timeouts in any of SDK objects (internally, all configuration objects passed in are consumed immediately to produce HTTP pipeline, so nothing is configurable after objects are created), to support overriding network timeouts for individual blob operations support for recreating whole stack of objects (service/container/blob) was added.
• Previously ETag updates were implicitly captured by storage SDK and a lot of code assumes fresh ETags are available after many operations, new SDK has updated ETag in some responses (which are all different types incompatible with each other), so call-specific etag capturing had to be added where available.
• Otherwise, I tried to make minimal changes to API surface we exposed, so that we don't spend time reworking downstream consumers of wrappers.

There are table wrappers using old SDK left that I haven't touched yet. Those are going to be addressed separately.

I commented out some tests and need some input on what to do with them.

The code was deployed to dev and passed E2E and functional tests.

There likely going to be more changes as this update is propagated to other repositories.

[erdembayar]

I see some WindowsAzure.Storage references in Infrastructure code. Are they covered in this PR?

[agr]

@erdembayar this is the reason I kept WindowsAzure.Storage reference in the csproj you asked about.