Doc of getproperty polluted by BunchKaufman and QRSparse

[mauro3]

Running ?Base.getproperty prints a long help text on extracting factors of above two factorizations. This is the wrong place for those to be: if I would look for them I would not type ?Base.getproperty and if I type ?Base.getproperty I certainly am not interested in those. They probably should be moved to the documentation of the types themselves, which is currently empty.
(Also, the types in some of the doc-strings are outdated due to stdlib-move)

X-ref: #25184
(Add Doc and LinearAlgebra labels)

[fredrikekre]

I feel like we don't need have docstrings for getproperty on those. Can't we just document the F.L etc accessors in the docstring for the factorization?