Refactor(durabletask): migrate to unified folder structure

[v-xuto]

This PR migrates the durabletask specification to the new unified folder structure according to Azure folder structure guidelines.

Change:

• Consolidated TypeSpec and Swagger files under resource-manager\Microsoft.DurableTask\DurableTask
• Updated tspconfig.yaml with correct paths and ARM types directory
• Fixed all common-types references and input-file paths in readme.md
• Verified TypeSpec compilation works correctly
• Updated the relevant paths in specification/suppressions.yaml file
• Add rpaas readme.md under resource-manger

Benefits:

• Unified structure for better maintainability
• Aligns with Azure folder structure standards
• Maintains backward compatibility
• Supports future TypeSpec migration efforts

[github-actions]

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[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

Language	API Review for Package
Swagger	Microsoft.DurableTask-DurableTask
TypeSpec	Microsoft.DurableTask
Go	sdk/resourcemanager/durabletask/armdurabletask
JavaScript	@azure/arm-durabletask
Python	azure-mgmt-durabletask
C#	Azure.ResourceManager.DurableTask
Java	com.azure.resourcemanager:azure-resourcemanager-durabletask

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