[FLINK-32733] Add AlgoOperator for FPGrowth

[vacaly]

What is the purpose of the change

Add AlgoOperator for FPGrowth.

FPGrowth is an algorithm for frequent pattern mining. Spark MLlib also provides this algorithm. FP growth algorithm represents the database in the form of a tree called a frequent pattern tree or FP tree.

[1] Han et al., Mining frequent patterns without candidate generation [2] Li et al., PFP Parallel FP-growth for query recommendation [3] Borgelt C. An Implementation of the FP-growth Algorithm

Brief change log

• Adds AlgoOperator implementation of FPGrowth in Java and Python
• Adds examples and documentations of FPGrowth
• Add keyedAggregate to DataStreamUtils.

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

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? docs / JavaDocs