[Improvement][datax] Support DataX parameter `batchSize` for writer

[bromine0x23]

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• [X] I had searched in the issues and found no similar feature requirement.

Description

Currently DataX task does not support writer parameter batchSize, therefore only the default values can be used, which is 2048.

However this default value is too small for some databases, such as the ClickHouse I'm using. The example value in DataX is 65536.

So I need the support of batchSize parameter.

Are you willing to submit a PR?

• [ ] Yes I am willing to submit a PR!

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