port: Fix invalid cast exception when sending delay activities through cloud adapter (#5617)

[github-actions]

The changes in Fix invalid cast exception when sending delay activities through cloud adapter (#5617) may need to be ported to maintain parity with microsoft/botbuilder-dotnet.

Fixes https://github.com/microsoft/BotFramework-Composer/issues/7880

Description

The cloud adapter tried to cast a delay activity's value to int. Because the value is an object, all numbers are boxed and therefore cannot be unboxed and cast to a different numeric type using a normal cast operation. We need to use Convert.ToInt32 instead.

The problem was also present in the test adapter so I've fixed it there too. The problem was not present in the Bot Framework HTTP adapter, but for the sake of completeness I've included a test for it anyway. The problem was present in the allow-null-ID test adapter and I fixed it there because I saw that it's supposed to mimic the other adapters, but I didn't include a test for it because it's not part of a public library.

Specific Changes

• Change (int) to Convert.ToInt32 in the cloud adapter, the test adapter, and the allow-null-ID test adapter
• Clean up some using statements
• Add delay tests

Testing

• CloudAdapterTests.CloudAdapterDelay
• BotFrameworkHttpAdapterTests.Delay
• TestAdapterTests.TestAdapter_Delay

Please review and, if necessary, port the changes.

[mrivera-ms]

Closing because this fix will be included in #1694