Add `NewColumn()` to `ColumnArray`

When inserting into Array columns, pg_clickhouse needs to create a new column matching the array's item type. The current API requires the verbose pattern:

CreateColumnByType(arrcol->GetType().As()->GetItemType()->GetName())

A NewColumn() method on ColumnArray that returns a properly typed column directly would simplify this and reduce the chance of type-name mismatches.

Start by locating ColumnArray and the existing CreateColumnByType path referenced in the issue, then inspect how array item types are represented. Done means ColumnArray exposes NewColumn() that returns a correctly typed column for its item type, with the repository’s relevant checks passing.

Written by the indexing model from the issue text.