Remove unnecessary Reducer conformance and @CasePathable macro in CaseStudies (#2567)

* remove unnecessary Reducer conformance

* remove unnecessary @CasePathable macro

---------

Co-authored-by: 강병민 <[email protected]>

Author: mike123789-dev

Examples/CaseStudies/SwiftUICaseStudies/04-HigherOrderReducers-Recursion.swift

@@ -11,14 +11,13 @@ private let readMe = """
 // MARK: - Feature domain
 
 @Reducer
-struct Nested: Reducer {
+struct Nested {
   struct State: Equatable, Identifiable {
     let id: UUID
     var name: String = ""
     var rows: IdentifiedArrayOf<State> = []
   }
 
-  @CasePathable
   enum Action {
     case addRowButtonTapped
     case nameTextFieldChanged(String)