[FEA] Add `sliced_child_begin()` and `sliced_child_end()` iterators for `column_view`

[ttnghia]

Currently, the column_view class offers the accessor child_begin() and child_end() iterators that allow iterating over the children of a column. However, when we want to access the sliced children column (in many places), we have to do that manually. It would be great if we can cache the sliced children and provide iterators sliced_child_begin() and sliced_child_end() that allow quickly iterating over them.

Since different classes (structs_column_view and lists_column_view) have different interfaces for generating column_view of sliced child, we may have to implement the proposed iterators separately in these classes instead of implementing in the column_view base class.

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[github-actions]

This issue has been labeled inactive-90d due to no recent activity in the past 90 days. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed.