feat(linear_algebra/tensor_power): Add notation for tensor powers, and a definition of multiplication (#14196)
feat(linear_algebra/tensor_power): Add notation for tensor powers, and a definition of multiplication (#14196)

This file introduces the notation `⨂[R]^n M` for `tensor_power R n M`, which in turn is an
abbreviation for `⨂[R] i : fin n, M`.

The proof that this multiplication forms a semiring will come in a later PR (#10255).





leanprover-community/mathlib,leanprover-community/mathlib