Revert broadening of arithmetic `Any` methods (revert #44564 and #45320) (#45489)
* Revert "Remove type-unlimited unary `+` and `*` (#45320)"
This reverts commit 990b1f3b1a254963bd71ceada44a560161225afb.
* Revert "Generalize or restrict a few basic operators (#44564)"
This reverts commit cf1f717700ada2784575c969d7114b3416e4f138.
Also fixes merge conflicts in stdlib/LinearAlgebra/test/generic.jl
Co-authored-by: Daniel Karrasch <daniel.karrasch@posteo.de>