making Bi/Tri/Sym times Diag output a structured matrix (not sparse) (#31889)
* making Bi/Tri/Sym times Diag output a structured matrix (not sparse)
* fix test errors/typos
* adding diag*bi/tri/sym and removing unused union
* add mul!(C,::BiTriSym, ::*Diagonal)
* fixing ambiguious methods and adjoint/transpose
* space
* test error
changing `transpose`/`adjoint` to `Transpose`/`Adjoint`
This will fail until https://github.com/JuliaLang/julia/pull/31889 is merged.
* remove transpose