Implement workflow inbox cleanup service

[sfmskywalker]

Closes #4295

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Summary

• Added new MemoryWorkflowInboxStore.cs to implement IWorkflowInboxStore interface
• Created SaveAsync(), FindManyAsync() and DeleteAsync() methods for MemoryWorkflowInboxStore class
• Added Filter() helper method to filter WorkflowInboxMessages

List of Changes:

• Added IWorkflowInboxStore interface implementation for MemoryWorkflowInboxStore.cs class
• Added constructor to MemoryWorkflowInboxStore.cs class that takes parameter of MemoryStore
• Added SaveAsync() method to save WorkflowInboxMessage instances in MemoryWorkflowInboxStore.cs
• Added FindManyAsync() method to search and retrieve WorkflowInboxMessages in MemoryWorkflowInboxStore.cs
• Added DeleteAsync() method to delete WorkflowInboxMessages in MemoryWorkflowInboxStore.cs
• Added Filter() helper method to filter WorkflowInboxMessages in MemoryWorkflowInboxStore.cs

Refactoring Target:

• Revise the memory store to use a read-write lock for thread safety
• Extract the filtering logic of the Filter() method into separate methods for readability
• Add logging to the SaveAsync(), FindManyAsync(), and DeleteAsync() methods to log any potential errors or exceptions
• Add unit tests to cover logic for MemoryWorkflowInboxStore class and its methods