[format] Support Map<X, Blob> type for Blob File Format

[steFaiz]

Purpose

Supports writing Map<X, Blob> in BlobFormatTable, following #8181

This PR only focus on Blob File Format of Java and Python module, keeping this PR reasonably small.
This PR DO NOT involes:

1. end-to-end support of Map<X, Blob> Type
2. Spark/Flink MergeInto support

Key Changes:

1. extract a new BlobElementSerializer to deal with blob elements: raw, array and map
2. implement BlobElementSerializer for Map<X, Blob>, where X only supports some simple non-nested type: String and Int family.

Tests

See unit tests

[JingsongLi]

cc @leaves12138 to take a look.

[JingsongLi]

Also support this in PrimaryKeyBlobExternalizer?

[steFaiz]

@JingsongLi Of course! But this PR only focus on file format layer modification. Wiring to Table & Engine layer will be brought in subsequent PRs.

I'm afraid that modifying all layers in one PR is too big to review.

[JingsongLi]

@JingsongLi Of course! But this PR only focus on file format layer modification. Wiring to Table & Engine layer will be brought in subsequent PRs.

I'm afraid that modifying all layers in one PR is too big to review.

@steFaiz It is OK in a single PR. It’s important to have a complete implementation; if we run into difficulties during the review, we’ll split the PR then.