Add Notebook, demonstrating saving and uploading of evaluators. (#2769)

# Description

In this PR we are adding the notebook, demonstrating saving and
uploading of the standard evaluator to Azure workspace or registry. At
the end of the notebook we are introducing function, uploading all the
evaluators in the given namespace.

# All Promptflow Contribution checklist:
- [x] **The pull request does not introduce [breaking changes].**
- [x] **CHANGELOG is updated for new features, bug fixes or other
significant changes.**
- [x] **I have read the [contribution guidelines](../CONTRIBUTING.md).**
- [x] **Create an issue and link to the pull request to get dedicated
review from promptflow team. Learn more: [suggested
workflow](../CONTRIBUTING.md#suggested-workflow).**

## General Guidelines and Best Practices
- [x] Title of the pull request is clear and informative.
- [x] There are a small number of commits, each of which have an
informative message. This means that previously merged commits do not
appear in the history of the PR. For more information on cleaning up the
commits in your PR, [see this
page](https://github.com/Azure/azure-powershell/blob/master/documentation/development-docs/cleaning-up-commits.md).

### Testing Guidelines
- [x] Pull request includes test coverage for the included changes.

.gitignore

@@ -191,3 +191,7 @@ config.json
 poetry.lock
 # promptflow subpackages __init__
 src/promptflow-*/promptflow/__init__.py
+
+# Eclipse project files
+**/.project
+**/.pydevproject