Update Network SDK to use API version 2019-09-01

[anton-evseev]

Description

• Added signed Network SDK package. We will replace it will SDK from NuGet once it's released (ETA: 10/23, before we merge our release branch into master)
• Updated test recordings (with some test modifications)
• Removed parts of ExpressRoute tests with "AzurePublicPeering" as this feature was deprecated
• Removed test ExpressRouteCircuitTests.TestExpressRouteLocalCircuit as server's behavior was changed, it no longer should throw an error
• Marked NetworkWatcherAPITests.TestProvidersList as skipped as this API isn't available to customers
• Removed UsageTestsGenerated as it's basically a duplciate of UsageTests
• Removed TestPublicIpAddressCRUD.json from the root of Network.Test. This was old recording that somehow ended up in wrong folder.

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • the markdown help files have been regenerated using the commands listed here

[anton-evseev]

@isra-fel please take a look. This PR is the base for #10323 and #10317 as they required API version 2019-09-01

[isra-fel]

It looks good to me

[isra-fel]

Fix CI error please @number213

Commands.Network.Test.ScenarioTests.AzureFirewallTests.TestAzureFirewallVirtualHubCRUD [FAIL]

[anton-evseev]

Given @isra-fel's approval, "waiting for CI" label and the need to unblock other PRs, I'll go ahead and merge this PR