[FLINK-28193][runtime] Enable to identify whether a job vertex contains source/sink operators

[zhuzhurk]

What is the purpose of the change

Speculative execution does not support sources/sinks in the first version. Therefore, it will not create speculation instances for vertices which contains source/sink operators.
Note that a job vertex with no input/output does not mean it is a true source/sink vertex:

• Multi-input sources can have input
• It's possible that the vertex with no output edge does not contain any sink operator
• A new sink with topology can spread the sink logic into multiple job vertices connected with job edges.

In this pr, we introduce methods to check whether a job vertex contains source/sink operators.

Verifying this change

• Added unit test StreamingJobGraphGeneratorSourceSinkTest

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[flinkbot]

CI report:

• 8011116 Azure: SUCCESS

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[zentol]

Could you not infer this from the size of inputs/results in the JobVertex?

[zhuzhurk]

Could you not infer this from the size of inputs/results in the JobVertex?

A job vertex with no input/output does not mean it is a true source/sink vertex.

• Multi-input sources can have input
• It's possible that the vertex with no output edge does not contain any sink operator
• A new sink with topology can spread the sink logic into multiple job vertices connected with job edges.

This was mentioned in the JIRA description. I will add it to the PR description.

[wanglijie95]

Thanks for creating this PR @zhuzhurk.
The changes look good to me. I only had one minor comment. Please take a look.

[zhuzhurk]

Thanks for the reviewing! @wanglijie95
Merging.