[DataFactory] Blob Events Trigger sample json

[cesher]

Description

Adding example for new Blob Events Trigger in Azure Data Factory, this trigger fires when an event happens in Blob Storage and can start a data processing workflow.

Swagger Spec PR: Azure/azure-rest-api-specs#3008

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• Please add REST spec PR link to the SDK PR
• I have read the contribution guidelines.
• The pull request does not introduce breaking changes.

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• If an SDK is being regenerated based on a new swagger spec, a link to the pull request containing these swagger spec changes has been included above.
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• The *.csproj and AssemblyInfo.cs files have been updated with the new version of the SDK.

[dsgouda]

• Please create a generate.ps1 file similar to this and commit changes to the txt file
• Please run msbuild build.proj /t:Build /p:Scope=SDKs\DataFactory and commit changes to the .props file
• There are some breaking changes introduced here, please bump the version number in csproj

[cesher]

Duplicate from #4360