[HUDI-3946] Validate option path in flink hudi sink

[yuruguo]

What is the purpose of the pull request

We should do a non-null check on option 'path' in flink hudi sink so that flink can expose the 'path' problem as early as possible, instead of throwing the error at runtime.

Caused by: java.lang.IllegalArgumentException: Can not create a Path from a null string
        at org.apache.hadoop.fs.Path.checkPathArg(Path.java:122) ~[hadoop-common-2.7.6.jar:?]
        at org.apache.hadoop.fs.Path.<init>(Path.java:134) ~[hadoop-common-2.7.6.jar:?]
        at org.apache.hudi.common.fs.FSUtils.getFs(FSUtils.java:103) ~[hudi-flink1.14-bundle_2.11-0.11.0-rc1.jar:0.11.0-rc1]
        at org.apache.hudi.util.StreamerUtil.tableExists(StreamerUtil.java:289) ~[hudi-flink1.14-bundle_2.11-0.11.0-rc1.jar:0.11.0-rc1]
        at org.apache.hudi.util.StreamerUtil.initTableIfNotExists(StreamerUtil.java:258) ~[hudi-flink1.14-bundle_2.11-0.11.0-rc1.jar:0.11.0-rc1]
        at org.apache.hudi.sink.StreamWriteOperatorCoordinator.start(StreamWriteOperatorCoordinator.java:172) ~[hudi-flink1.14-bundle_2.11-0.11.0-rc1.jar:0.11.0-rc1]
        at org.apache.flink.runtime.operators.coordination.OperatorCoordinatorHolder.start(OperatorCoordinatorHolder.java:194) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.scheduler.DefaultOperatorCoordinatorHandler.startAllOperatorCoordinators(DefaultOperatorCoordinatorHandler.java:85) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.scheduler.SchedulerBase.startScheduling(SchedulerBase.java:584) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.jobmaster.JobMaster.startScheduling(JobMaster.java:965) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.jobmaster.JobMaster.startJobExecution(JobMaster.java:882) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.jobmaster.JobMaster.onStart(JobMaster.java:389) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.rpc.RpcEndpoint.internalCallOnStart(RpcEndpoint.java:181) ~[flink-dist_2.11-1.14.2.jar:1.14.2]
        at org.apache.flink.runtime.rpc.akka.AkkaRpcActor$StoppedState.lambda$start$0(AkkaRpcActor.java:624) ~[flink-rpc-akka_a8af7b4c-9c0c-4ac4-a1b1-1690068e50df.jar:1.14.2]
        at org.apache.flink.runtime.concurrent.akka.ClassLoadingUtils.runWithContextClassLoader(ClassLoadingUtils.java:68) ~[flink-rpc-akka_a8af7b4c-9c0c-4ac4-a1b1-1690068e50df.jar:1.14.2]
        at org.apache.flink.runtime.rpc.akka.AkkaRpcActor$StoppedState.start(AkkaRpcActor.java:623) ~[flink-rpc-akka_a8af7b4c-9c0c-4ac4-a1b1-1690068e50df.jar:1.14.2]
        ... 20 more 

more detial

Brief change log

(for example:)

• Modify AnnotationLocation checkstyle rule in checkstyle.xml

Verify this pull request

(Please pick either of the following options)

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

(or)

This pull request is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end.
• Added HoodieClientWriteTest to verify the change.
• Manually verified the change by running a job locally.

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.

[hudi-bot]

CI report:

• 28962d5 Azure: SUCCESS

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