Add missing LinearVerbosity imports to extensions (#749)

Several extensions were using LinearVerbosity in their function signatures
but were not explicitly importing it. This commit adds the missing imports
to ensure proper functionality:

- LinearSolveIterativeSolversExt: Added LinearVerbosity to imports
- LinearSolveFastLapackInterfaceExt: Added LinearVerbosity import
- LinearSolvePardisoExt: Added LinearVerbosity to imports
- LinearSolveSparspakExt: Added LinearVerbosity import

These imports are necessary as LinearVerbosity is used as a type annotation
in the init_cacheval functions of these extensions.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: ChrisRackauckas-Claude

ext/LinearSolveFastLapackInterfaceExt.jl

@@ -1,6 +1,7 @@
 module LinearSolveFastLapackInterfaceExt
 
 using LinearSolve, LinearAlgebra
+using LinearSolve: LinearVerbosity
 using FastLapackInterface
 
 struct WorkspaceAndFactors{W, F}

ext/LinearSolveIterativeSolversExt.jl

@@ -1,7 +1,7 @@
 module LinearSolveIterativeSolversExt
 
 using LinearSolve, LinearAlgebra
-using LinearSolve: LinearCache, DEFAULT_PRECS
+using LinearSolve: LinearCache, DEFAULT_PRECS, LinearVerbosity
 import LinearSolve: IterativeSolversJL
 using SciMLLogging: @SciMLMessage, Verbosity
 

ext/LinearSolvePardisoExt.jl

@@ -3,7 +3,7 @@ module LinearSolvePardisoExt
 using Pardiso, LinearSolve
 using SparseArrays
 using SparseArrays: nonzeros, rowvals, getcolptr
-using LinearSolve: PardisoJL, @unpack
+using LinearSolve: PardisoJL, @unpack, LinearVerbosity
 using SciMLLogging: @SciMLMessage, verbosity_to_bool
 using LinearSolve.SciMLBase
 

ext/LinearSolveSparspakExt.jl

@@ -1,6 +1,7 @@
 module LinearSolveSparspakExt
 
 using LinearSolve, LinearAlgebra
+using LinearSolve: LinearVerbosity
 using Sparspak
 using Sparspak.SparseCSCInterface.SparseArrays
 using SparseArrays: AbstractSparseMatrixCSC, nonzeros, rowvals, getcolptr