feat(ring_theory/adjoin/basic): add missing lemmas (#7780)
feat(ring_theory/adjoin/basic): add missing lemmas (#7780)

Two missing lemmas about `adjoin`.

These are the `subalgebra` versions of `submodule.span_eq_of_le` and `submodule.span_eq`.






leanprover-community/mathlib,leanprover-community/mathlib