[Feature Request] Using different names when saving training and testing log.

[jbwang1997]

Describe the feature

For now, mmengine also save testing log in work_dirs. However, the folder names of traning and testing logs are both in the same pattern. After testing model several times, it's hard to find the training log.

If possible, it's better to use 20221101_094140_train or 20221101_094140_test to distinguish the training and testing logs.

Motivation
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Related resources
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Additional context
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If you would like to implement the feature and create a PR, please leave a comment here and that would be much appreciated.

[HAOCHENYE]

We'll enhance it in the next version.