Python: Use overloads for sk function invoke_* calls

[awharrison-28]

Motivation and Context

It is confusing to have multiple skfunction invoke_* calls. This PR combines invoke and invoke_with_vars to enable calls with the input pattern: with SKContext, or with SKContextVariables.

Description

• Removed sk_function methods invoke_with_vars and invoke_with_vars_async
• Added the following optional paramters to sk_function methods invoke_ and invoke_async: variables and memory
• Added log warnings for when an both SKContext and variables/memory are passed to invoke methods - this design ensures that the SDContext and it's associated variables and memory are prioritized
• Updated tests and notebooks where applicable

Contribution Checklist

• [x] The code builds clean without any errors or warnings
• [x] The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
• [x] The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• [x] All unit tests pass, and I have added new tests where possible
• [x] I didn't break anyone :smile: