Temporary workaround for handling Http NotFound exception in MemoryStoreExtender

[LuisM000]

Description

This pull request addresses an issue related to issue (though it does not close it). The PR introduces a temporary fix for an error identified in Semantic Kernel. The issue arises when utilizing the AzureAISearch connector, specifically when attempting to retrieve data from the memory store for a non-existent item. Instead of gracefully handling this scenario by returning null, an exception is thrown.

Changes Made

• Implements a temporary fix to handle the Http NotFound exception in the MemoryStore.GetAsync method.
• Adds a try-catch block to capture the exception and prevent disruption in case of a non-existent item in the memory store.
• Includes a note in the code to emphasize that this fix is temporary and should be removed once the underlying issue in Semantic Kernel is resolved.

Note: This fix is introduced to mitigate the current behavior of the AzureAISearch Memory Store until a permanent solution is provided in Semantic Kernel.

Related Issues

• Fixes issue #72 indirectly by addressing a specific error mentioned in the issue.

[LuisM000]

I'm aware that this PR will close issue #72 because it's referenced. I understand, and I'll reopen it once the PR is completed :)