feat(data/matrix/kronecker): add two lemmas (#8700)
feat(data/matrix/kronecker): add two lemmas (#8700)

Added two lemmas `kronecker_map_assoc` and `kronecker_assoc` showing associativity of the Kronecker product



Co-authored-by: Filippo A. E. Nuccio <c738690ea344e18cc24d151a9efeeb2f70b499fb@users.noreply.github.com>
Co-authored-by: Eric Wieser <da64e90baec5d084ce3d8e05f3b022ae6d118ff5@gmail.com>

leanprover-community/mathlib,leanprover-community/mathlib