mathlib

8422d8c7 - chore(data/padics): move padics to number_theory/ (#7771)

chore(data/padics): move padics to number_theory/ (#7771) Per [zulip](https://leanprover.zulipchat.com/#narrow/stream/113488-general/topic/move.20p-adics). Co-authored-by: Scott Morrison <scott.morrison@gmail.com>