Python: Context providers abstraction and Mem0 implementation (#631)

* Added context provider abstractions

* Added mem0 implementation

* Example and small fixes

* Added unit tests for agent

* Added unit tests for mem0 provider

* Updated README

* Small doc updates

* Update python/packages/mem0/agent_framework_mem0/_provider.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Small fixes in tests

* Renaming based on PR feedback

* Small fixes

* Added tests for AggregateContextProvider

* Small improvements

* More improvements based on PR feedback

* Small constant update

* Added more examples

* Added README for Mem0 examples

* Small updates to API

* Updated initialization logic

* Updates for context manager

* Updated Context class

* Dependency update

* Revert changes

* Fixed tests

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Chris <66376200+crickman@users.noreply.github.com>

python/packages/mem0/README.md

@@ -0,0 +1,21 @@
+# Get Started with Microsoft Agent Framework Mem0
+
+Please install this package as the extra for `agent-framework`:
+
+```bash
+pip install agent-framework[mem0]
+```
+
+## Memory Context Provider
+
+The Mem0 context provider enables persistent memory capabilities for your agents, allowing them to remember user preferences and conversation context across different sessions and threads.
+
+### Basic Usage Example
+
+See the [Mem0 basic example](https://github.com/microsoft/agent-framework/tree/main/python/samples/getting_started/context_providers/mem0/mem0_basic.py) which demonstrates:
+
+- Setting up an agent with Mem0 context provider
+- Teaching the agent user preferences
+- Retrieving information using remembered context across new threads
+- Persistent memory
+