.Net: Prompty Code cleanup

[LittleLittleCloud]

Adding more tests to cover the new code in PromptTemplate.Prompty and Function.Prompty

### Tasks
- [x] Add more test for PromptTemplate.Prompty and FunctionPrompty
- [ ] As far as the spec is concerned, the name is strictly considered metadata - if we need to extract a useful function name, my sense is that the filename (sans extension) would be a better candidate.
- [ ] Test with IAIServiceSelector, see https://github.com/microsoft/semantic-kernel/pull/5961#discussion_r1578726198
- [ ] We support some additional properties, IsRequest, JsonSchema, AllowUnfaceContent https://github.com/microsoft/semantic-kernel/pull/5961#discussion_r1579262436
- [ ] Add input fields in chat.prompty https://github.com/microsoft/semantic-kernel/pull/5961#discussion_r1579154292
- [ ] Supporting additional models https://github.com/microsoft/semantic-kernel/pull/5961#discussion_r1579170026
- [ ] Support model specific execution settings https://github.com/microsoft/semantic-kernel/pull/5961#discussion_r1579164960
- [ ] Add logging to LiquidPromptTemplate https://github.com/microsoft/semantic-kernel/pull/6048#discussion_r1589796510

[github-actions]

This issue is stale because it has been open for 90 days with no activity.