feat(data/finsupp/basic): Add `finsupp.erase_of_not_mem_support` (#10689)
feat(data/finsupp/basic): Add `finsupp.erase_of_not_mem_support` (#10689)

Analogous to `list.erase_of_not_mem`






leanprover-community/mathlib,leanprover-community/mathlib