[HUDI-8401] Add merger classes for CDC payloads.

[linliu-code]

Change Logs

Add merger classes for CDC payloads.

Impact

These classes will replace the usage of CDC payload classes.

Risk level (write none, low medium or high below)

Medium.

Documentation Update

Describe any necessary documentation update if there is any new feature, config, or user-facing change. If not, put "none".

• The config description must be updated if new configs are added or the default value of the configs are changed
• Any new feature or user-facing change requires updating the Hudi website. Please create a Jira ticket, attach the ticket number here and follow the instruction to make changes to the website.

Contributor's checklist

• [ ] Read through contributor's guide
• [ ] Change Logs and Impact were stated clearly
• [ ] Adequate tests were added if applicable
• [ ] CI passed

[hudi-bot]

CI report:

• e079c6035dd861b1683040f5c52ce8cfdd9c6d99 Azure: SUCCESS

Bot commands

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• @hudi-bot run azure re-run the last Azure build