mathlib3

98f2779c - refactor(number_theory/legendre_symbol/*): move section `general` from `quadratic_char.lean` into new file `auxiliary.lean` (#14027)

refactor(number_theory/legendre_symbol/*): move section `general` from `quadratic_char.lean` into new file `auxiliary.lean` (#14027) This is a purely administrative step (in preparation of adding more files that may need some of the auxiliary results). We move the collection of auxiliary results that constitute `section general` of `quadratic_char.lean` to a new file `auxiliary.lean` (and change the `import`s of `quadratic_char.lean` accordingly). This new file is meant as a temporary place for these auxiliary results; when the refactor of `quadratic_reciprocity` is finished, they will be moved to appropriate files in mathlib.