Enable SwiftLint rule 'static_operator' and fix all violations

.swiftlint.yml

@@ -170,7 +170,7 @@ only_rules:
   - sorted_first_last
 #  - sorted_imports # Managed by SwiftFormat.
   - statement_position
-#  - static_operator
+  - static_operator
   - strict_fileprivate
   - strong_iboutlet
   - superfluous_disable_command

passKit/Parser/AdditionField.swift

@@ -38,6 +38,9 @@ extension AdditionField {
 }
 
 infix operator =>: MultiplicationPrecedence
-public func => (key: String, value: String) -> AdditionField {
+
+public extension String {
+    static func => (key: String, value: String) -> AdditionField {
         AdditionField(title: key, content: value)
     }
+}

passKitTests/Testbase/TestBase.swift

@@ -50,11 +50,14 @@ func assertDefaults(
 }
 
 infix operator ∈: AdditionPrecedence
-func ∈ (field: AdditionField, password: Password) -> Bool { // swiftlint:disable:this identifier_name
+infix operator ∉: AdditionPrecedence
+
+extension AdditionField {
+    static func ∈ (field: AdditionField, password: Password) -> Bool { // swiftlint:disable:this identifier_name
         password.getFilteredAdditions().contains(field)
     }
 
-infix operator ∉: AdditionPrecedence
-func ∉ (field: AdditionField, password: Password) -> Bool { // swiftlint:disable:this identifier_name
+    static func ∉ (field: AdditionField, password: Password) -> Bool { // swiftlint:disable:this identifier_name
         !(field ∈ password)
     }
+}