fix: [#6683] Timeout issue when using DLASE

[sw-joelmut]

Fixes #6683

Description

This PR fixes an issue where, while using DLASE, the bot threw a timeout issue while streaming, due to not generating a response in the initial request. Therefore, if the streaming process in the initial request takes longer than 15 seconds to finalize and generate a response, the bot will throw a timeout issue. Sending a response (HTTP 202 (Accepted)) before starting to process all streaming requests addressed the issue and will not generate a timeout issue.

Specific Changes

• Add SendResponseAsync call to the StreamingSession class to send an HTTP 202 (Accepted) response before starting processing all streaming information.
• Add Accepted StatusCode condition to ProtocolAdapter for Streaming and StreamingSession for Connector.Streaming. This allows to detect when the Accepted response is taking place and can proceed to ignore the response and let the actual OK response to be used after streaming.

Testing

The following image shows the timeout issue before and after the fix.

Note: consistently was timing out around 25 to 35 activities, with the fix, it is no longer the case.

[tracyboehrer]

@sw-joelmut It appears some Microsoft.Bot.Connector.Streaming.Tests are failing.

[coveralls]

Pull Request Test Coverage Report for Build 371447

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 20 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.004%) to 73.455%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetNextViableTime.cs	1	90.91%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetPreviousViableTime.cs	1	90.91%
/libraries/Microsoft.Bot.Connector.Streaming/Application/TimerAwaitable.cs	1	68.25%
/libraries/Microsoft.Bot.Connector.Streaming/Session/StreamingSession.cs	17	91.2%
<!--	Total:	20		-->

Totals
Change from base Build 369561:	0.004%
Covered Lines:	24147
Relevant Lines:	32873

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💛 - Coveralls

[BruceHaley]

:heavy_check_mark: No Binary Compatibility issues for Microsoft.Bot.Streaming.dll

[sw-joelmut]

@sw-joelmut It appears some Microsoft.Bot.Connector.Streaming.Tests are failing.

Changes applied, and updated the PR's description, thanks!