mathlib

325dbc88 - refactor(number_theory/legendre_symbol/quadratic_reciprocity.lean): change definition of legendre_sym, simplify proofs, add lemmas (#13667)

refactor(number_theory/legendre_symbol/quadratic_reciprocity.lean): change definition of legendre_sym, simplify proofs, add lemmas (#13667) This changes the definition of `legendre_sym` to use `quadratic_char`. The proof of some of the statements can then be simplified by using the corresponding statements for quadratic characters. Some new API lemmas are added, including the fact that the Legendre symbol is multiplicative, Also, a few `simps` are squeezed in `.../quadratic_char.lean`.