[FLINK-38352][table-planner] Make source specs forward compatible (like sink specs)

[twalthr]

What is the purpose of the change

For consistency reason, WatermarkPushDownSpec can be forward-compatible. While implementing this, I noticed that all sinks specs are forward compatible but not the source specs. This adds consistency. A general ignoring of unknown properties should be avoided, however, because this could lead to unintended side effects.

Brief change log

Add @JsonIgnoreProperties(ignoreUnknown = true) to all source specs

Verifying this change

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

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

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

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

[flinkbot]

CI report:

• e78cd25 Azure: FAILURE
• 22a4900 Azure: PENDING

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[twalthr]

@flinkbot run azure

[davidradl]

@twalthr could we can add unit tests for these changes?

[twalthr]

@davidradl this is not officially supported behavior. we don't claim forward compatibility at all. I just added it for code consistency.