[CodeCamp2023-Task288] Add NeptuneVisBackend

[wangerlie]

Motivation

CodeCamp2023

Modification

1. Add Neptune backend to visualizer. The original task is to add segmind, however the mentor suggest to use Neptune as backend instead after searching the docs about segmind and finding that it does not suit for the task.

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repos?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

NO

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

NO

Checklist

add aditional unit test for Neptune backend test

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects, like MMDet or MMCls.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[CLAassistant]

All committers have signed the CLA.

[zhouzaida]

Hi @wangerlie , thanks for your contribution. Could you help add the usage of Neptune in docs/zh_cn/common_usage/visualize_training_log.md and docs/en/common_usage/visualize_training_log.md.

In addition, please also add NeptuneVisBackend in docs/en/api/visualization.rst and docs/en/api/visualization.rst.