LINQPad 6 support and Azure SDK Update

It took a while for a new version to come out, but with LINQPad 6
and big changes in the Azure SDK libraries, I thought it was time.
And, although functionally not much has changed, I decided that a new
distribution channel and total change in the underlying SDK,
deserved a new major version.

• New: Available as a Nuget package for LINQPad 6.
• Switch to Azure Cosmos DB Table API
  • LINQPad 6 plugin uses Microsoft.Azure.Cosmos.Table 1.0.5
  • LINQPad 5 plugin uses Microsoft.Azure.CosmosDB.Table 2.1.2

Note: the Azure Storage SDK used by the LINQPad 5 version is in maintenance mode
and it will be deprecated soon according to Microsoft. However, since LINQPad 5
plugins target .NET Framework 4.6, the switch to the package used by the LINQPad 6
plugin is not possible.