Bug description
When using az storage blob sync to synchronize files to an Azure storage blob container, .js files get content-type text/plain.

Expected behavior
Content type should be application/javascript.

Environment summary

• azure-cli 2.0.70
• command-modules-nspkg 2.0.3
• core 2.0.70 **
• nspkg 3.0.4
• telemetry 1.0.3
• Extension: azure-devops 0.12.0
• Running in Azure DevOps task 'Azure CLI' version 1.155.1

Additional context
Using Azure DevOps task 'AzCopy' instead yields the correct content type.