### Motivation and Context

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Address feature request:
microsoft#10174

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->
This pull request introduces a new decorator for tracing agent
invocations and applies it to various methods in the
`ChatCompletionAgent` and `OpenAIAssistantAgent` classes. Additionally,
it includes new unit tests to ensure the decorator is correctly applied
and functions as expected.

### Key Changes:

**Decorator Implementation:**
* Added a new `trace_agent_invocation` decorator in
`python/semantic_kernel/utils/telemetry/agent_diagnostics/decorators.py`
to trace agent invocations using OpenTelemetry.

**Decorator Application:**
* Applied the `trace_agent_invocation` decorator to the `invoke` and
`invoke_stream` methods in `ChatCompletionAgent`
(`python/semantic_kernel/agents/chat_completion/chat_completion_agent.py`).
[[1]](diffhunk://#diff-0f0a27c107368504c4347c88528b7b4234dcead1919005bcae13f5d16d6cf26dR19)
[[2]](diffhunk://#diff-0f0a27c107368504c4347c88528b7b4234dcead1919005bcae13f5d16d6cf26dR80)
[[3]](diffhunk://#diff-0f0a27c107368504c4347c88528b7b4234dcead1919005bcae13f5d16d6cf26dR134)
* Applied the `trace_agent_invocation` decorator to the `invoke` and
`invoke_stream` methods in `OpenAIAssistantAgent`
(`python/semantic_kernel/agents/open_ai/open_ai_assistant_base.py`).
[[1]](diffhunk://#diff-70e75c57136d3a90d045af4b8d59fb8e8101251d7c5126458bb5d9e6c36556a4R46)
[[2]](diffhunk://#diff-70e75c57136d3a90d045af4b8d59fb8e8101251d7c5126458bb5d9e6c36556a4R608)
[[3]](diffhunk://#diff-70e75c57136d3a90d045af4b8d59fb8e8101251d7c5126458bb5d9e6c36556a4R861)

### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [x] The code builds clean without any errors or warnings
- [x] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [x] All unit tests pass, and I have added new tests where possible
- [x] I didn't break anyone 😄

---------

Co-authored-by: Evan Mattson <[email protected]>