[HUDI-542] Introduce a new pom module named hudi-writer-common

[yanghua]

What is the purpose of the pull request

This pull request introduces a new pom module named hudi-writer-common

Brief change log

• Introduce a new pom module named hudi-writer-common

Verify this pull request

This pull request is a trivial rework / code cleanup without any test coverage.

Committer checklist

• Has a corresponding JIRA in PR title & commit

• Commit message is descriptive of the change

• CI is green

• Necessary doc changes done or have another open PR

• For large changes, please consider breaking it into sub-tasks under an umbrella JIRA.

[yanghua]

@vinothchandar @leesf FYI: new module hudi-writer-common on restructure-hudi-client.

[vinothchandar]

@yanghua ack. Do we need a feature branch for this work? can't we do this on master with incremental commits

[yanghua]

@yanghua ack. Do we need a feature branch for this work? can't we do this on master with incremental commits

A new module will be added here. If we copy related class files from hudi-client to the new module instead of moving those class files. it can theoretically be completed on the master branch

However, as a relatively large work (we will eventually move some classes in the hubi-client to other modules), it will be more reasonable to verify it on an independent branch to see whether those PRs can pass then migrate them to the master branch, which will not affect the master branch.

[vinothchandar]

@yanghua as I also mentioned on the JIRA. What you suggest makes sense when we are in the phase of separating hudi-spark and hudi-writer-common.. This model also makes for us to take the hit of rebasing, without thrashing all existing PRs.