mathlib

6f2d1ba2 - feat(data/dfinsupp): add submodule.bsupr_eq_range_dfinsupp_lsum (#9202)

feat(data/dfinsupp): add submodule.bsupr_eq_range_dfinsupp_lsum (#9202) Also a version for `add_submonoid`. Unfortunately the proofs are almost identical, but that's consistent with the surrounding bits of the file anyway. The key result is a dfinsupp version of the lemma in #8246, ```lean x ∈ (⨆ i (H : p i), f i) ↔ ∃ v : ι →₀ M, (∀ i, v i ∈ f i) ∧ ∑ i in v.support, v i = x ∧ (∀ i, ¬ p i → v i = 0) := ``` as ```lean x ∈ (⨆ i (h : p i), S i) ↔ ∃ f : Π₀ i, S i, dfinsupp.lsum ℕ (λ i, (S i).subtype) (f.filter p) = x ```