Resolve all method ambiguities in LinearAlgebra (#28749)
* Add a test to check method ambiguities
* Use StridedMatrix to avoid method ambiguity; fixes #27405
* Avoid method ambiguity in promote_leaf_eltypes
This change is only for making Test.detect_ambiguities and shouldn't
introduce any change in working code (unless it depends on MethodError).
Before this change, we have:
julia> LinearAlgebra.promote_leaf_eltypes(())
ERROR: MethodError: LinearAlgebra.promote_leaf_eltypes(::Tuple{}) is ambiguous. Candidates:
With this change, we have:
julia> LinearAlgebra.promote_leaf_eltypes(())
Bool
