## What changes were proposed in this pull request?
Logically the `Array` doesn't belong to `ColumnVector`, and `Row` doesn't belong to `ColumnarBatch`. e.g. `ColumnVector` needs to return `Array` for `getArray`, and `Row` for `getStruct`. `Array` and `Row` can return each other with the `getArray`/`getStruct` methods.
This is also a step to make `ColumnVector` public, it's cleaner to have `Array` and `Row` as top-level classes.
This PR is just code moving around, with 2 renaming: `Array` -> `VectorBasedArray`, `Row` -> `VectorBasedRow`.
## How was this patch tested?
existing tests.
Author: Wenchen Fan <wenchen@databricks.com>
Closes#19740 from cloud-fan/vector.
dce1610ae3