[FLINK-38807][state] Add state SQL metadata based type inference

[gaborgsomogyi]

What is the purpose of the change

This PR enhances SQL state API internally to infer savepoint types from savepoint metadata which eliminates almost all value-class and key-type-factory SQL option usages. The trick is simple, use serializers coming from metadata. Serialized classes still needs to be on classpath.

Brief change log

• Automatic savepoint type inference based on savepoint metadata
• In test changed MAP<bigint, bigint> type to MAP<string, bigint> to introduce difference
• Fixed map key and value proper type inference
• Updated docs

Verifying this change

Modified tests.

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:

• 34c44c9 Azure: SUCCESS

Bot commands

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

[davidradl]

We should deprecate classes rather than just remove, and give advice on how to move to the new way of doing things. I suppose this could be a back port consideration only - if we take this approach then a comment reminder would be good.

[gaborgsomogyi]

Deprecate from test code?🙂 The new way is that Flink finds this out automatically but the SavepointTypeInformationFactory approach remains as safety belt.

[davidradl]

@gaborgsomogyi my bad. I did not look closely enough. If the SavepointTypeInformationFactory approach remains as safety belt, I suggest we keep the deleted tests that refer to this approach - I assume these tests would still work if there is no metadata.

[gaborgsomogyi]

They're working but the whole intention is is to infer types and make user's life easier. The SavepointTypeInformationFactory approach would worth to add a new test though

[gaborgsomogyi]

Added test coverage