Explicitly declare type constructor imports (#598)

These would otherwise give a warning after JuliaLang/julia#57311, but
are a good change even independently.

Author: Keno

src/SparseArrays.jl

@@ -15,6 +15,7 @@ using LinearAlgebra: AdjOrTrans, AdjointFactorization, TransposeFactorization, m
 
 
 import Base: +, -, *, \, /, ==, zero
+import Base: Matrix, Vector
 import LinearAlgebra: mul!, ldiv!, rdiv!, cholesky, adjoint!, diag, eigen, dot,
     issymmetric, istril, istriu, lu, tr, transpose!, tril!, triu!, isbanded,
     cond, diagm, factorize, ishermitian, norm, opnorm, lmul!, rmul!, tril, triu,