.Net: Allow strings to be passed for int arguments in TextSearch KernelFunctions

[lossyrob]

Motivation and Context

The GetArgumentValue method that is called as part of creating KernelFunctions for TextSearch in TestSearchExtensions requires that arguments be passed as integers for "count" and "skip". While using this functionality with a gpt-4o model through Azure OpenAI, the function calls were given arguments that had values encoded as strings. This caused the default count of 2 to always be used, no matter what the LLM was calling for. I noticed this behavior even if I explicitly set the ParameteryType of the KernelParameterMetadata to be int.

Description

This changes the GetArgumentValue method in TextSearchExtensions to allow for integers passed as string values. This will avoid the confusing behavior of the arguments being ignored for TextSearch plugins.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄