Add Subito custom reporter

Source/SwiftLintCore/Models/ReportersList.swift

@@ -16,6 +16,7 @@ public let reportersList: [any Reporter.Type] = [
     RelativePathReporter.self,
     SARIFReporter.self,
     SonarQubeReporter.self,
+    SubitoReporter.self,
     SummaryReporter.self,
     XcodeReporter.self
 ]

Source/SwiftLintCore/Reporters/SubitoReporter.swift

@@ -0,0 +1,28 @@
+/// Reports violations in the custom Subito format.
+struct SubitoReporter: Reporter {
+    // MARK: - Reporter Conformance
+
+    static let identifier = "subito"
+    static let isRealtime = true
+    static let description = "Reports violations in the custom Subito format."
+
+    static func generateReport(_ violations: [StyleViolation]) -> String {
+        violations.map(generateForSingleViolation).joined(separator: "\n")
+    }
+
+    /// Generates a report for a single violation.
+    ///
+    /// - parameter violation: The violation to report.
+    ///
+    /// - returns: The report for a single violation.
+    static func generateForSingleViolation(_ violation: StyleViolation) -> String {
+        // {error,warning}
+        //   {full_path_to_file}{:line}{:character}
+        //   {content} - {content}
+        """
+        \(violation.severity.rawValue)
+          \(violation.location)
+          \(violation.ruleName) Violation - \(violation.reason) \(violation.ruleIdentifier)
+        """
+    }
+}