Support Text summary in Experiment TensorBoard

Hello,

I'm migrating some ML tasks to Vertex AI and really like the Experiment framework.

My current setup is:
- submitting CustomJob tasks from a custom training image
- group these tasks in an Experiment, to enable an easy comparison between those
- the training script is adapted to log information both to Experiment (with the Python SDK, e.g. `log_time_series_metrics()`) and to the CustomJob TB (standard SummaryWriter in the `AIP_TENSORBOARD_LOG_DIR`), following the documentation

It's all very convenient, but there is one thing I cannot do with Experiment.
The Python SDK does not support text uploads (and hparams but that's not crucial), and it's very important for NLP or ASR training tasks.
This is how it looks like in my CustomJob TB:

I'm opening this feature request as this would be a handsome addition to the Experiment framework.

Thank you for your work, don't hesitate if I can provide more input.

首先查看 Python SDK 的 Experiment 日志记录 API，以及有关 CustomJob TensorBoard logs 的参考文档。定义受支持的文本摘要行为，并验证上传的文本是否与现有指标一起显示在 Experiment TensorBoard 中；该 issue 未指定具体文件或测试。

由索引模型根据 Issue 内容生成。