We introduce a construction functor for invariant and equivariant submodules.

sage.modules.with_basis.invariant.FiniteDimensionalInvariantModule gets a construction method.

In follow-up ticket #34499, also the tensor modules with prescribed monoterm symmetries from #30229 will get a construction method. An illustration of this application, capturing symmetric and antisymmetric matrices, is included as an example. (See #32029, #30276.)

CC: @tscrim @trevorkarn @egourgoulhon @anneschilling

Component: linear algebra

Author: Matthias Koeppe

Branch/Commit: 7fe5763

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/34495