port: [#6861]TeamsSSOTokenExchangeMiddleware.DeduplicatedTokenExchangeIdAsync fails on BlobStorage ETag validation

[ceciliaavila]

#minor

Description

This PR ports the changes from [BotBuilder-DotNet's PR#6867](https ://github.com/microsoft/botbuilder-dotnet/pull/ 6867) to handle eTag conflicts on concurrent calls to the BlobsStorage write method.

Specific Changes

• Added a try-catch block to handle the 412 error code in the write method of BlobsStorage class.
• Added a unit test to cover this scenario in blobsStorage.tests.js.

Testing

This image shows the new unit tests working.

[coveralls]

Pull Request Test Coverage Report for Build 11955774357

Details

• 0 of 8 (0.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.02%) to 84.689%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
libraries/botbuilder-azure-blobs/src/blobsStorage.ts	0	8	0.0%

Totals
Change from base Build 11691458662:	-0.02%
Covered Lines:	20515
Relevant Lines:	23068

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💛 - Coveralls

[ceciliaavila]

/promoted 4800