.Net: Example with native functions using custom types - #3255

### Motivation and Context

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This PR contains changes to add new examples how to use native functions
with custom types.

Examples include:
1. One native function calls another native function (function
chaining).
2. Two native functions are called sequentially in Kernel (function
pipeline).
3. Auto conversion of context variables to primitive types in native
function parameters.

### Contribution Checklist

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