[Python] Port MathSkill from C# to python3

[poweihuang0817]

Motivation and Context

Port MathSkill from C# to python3. This is essential for advanced skill like plan

Description

The PR includes two part. The first part is an implementation of MathSkill. The implementation follows C# version. It does several things:

1. Parse initial value
2. Get value from context
3. Sum or subtract

The unit test covers these scenarios:

1. Add/subtract value
2. Error should throw if string is not correct. Not able to parse.

Last part is the init.py and feature matrix. Unit test pass locally.

Contribution Checklist

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