[Umbrella][Feature] Support for complex data types

### Search before asking

- [x] I searched in the [issues](https://github.com/alibaba/fluss/issues) and found nothing similar.

### Motivation

Support for complex data types: Array ([#168](https://github.com/alibaba/fluss/issues/168)), Map ([#169](https://github.com/alibaba/fluss/issues/169)), Struct ([#170](https://github.com/alibaba/fluss/issues/170)), Variant/JSON.

**Task list**
- [x] Support for Row Type Foundation @XuQianJin-Stars
- [x] Support for Array data type @XuQianJin-Stars
- [x] Support for Map data type @XuQianJin-Stars
- [x] Support for Struct data type @XuQianJin-Stars
- [ ] Support for Variant/JSON data type

### Solution

1. The interface layer will implement: `InternalArray`, `InternalMap`, and `InternalRow` (to be refined).
2. Add generic implementations: `GenericArray`, `GenericMap`, and `GenericRow` (to be refined).
3. Implement `ArrayType`, `MapType`, `StructType`, `Variant/JSON`, etc., based on Arrow (`ColumnarRow`), `IndexedRow`, and `CompactedRow` respectively.
4. Integrate and transform with Flink/Spark data types.
5. Integrate and transform with data lakes (such as Paimon).

### Anything else?

_No response_

### Willingness to contribute

- [x] I'm willing to submit a PR!

Start with the remaining Variant/JSON item in the task list and review the proposed InternalArray, InternalMap, and InternalRow interfaces alongside the generic implementations and Arrow-based types described in the solution. Trace the planned Flink/Spark and data-lake integrations, then define completion as Variant/JSON support integrated across the listed layers and reflected by a completed task-list item.

Written by the indexing model from the issue text.