Add `DecimalBaseColumn` and move `as_decimal_column`#9001

Merged

rapids-bot[bot] merged 4 commits intorapidsai:branch-21.10from isVoid:8853

Aug 13, 2021

+55-30

Commits on Aug 9, 2021

Initial
isVoid
committed

Commits on Aug 11, 2021

Commits on Aug 13, 2021

style
isVoid
committed