Modify PrettyPrinter to output diagnostics using shortened relative paths

Author: TTOzzi

Sources/SwiftFormat/PrettyPrint/PrettyPrint.swift

@@ -816,10 +816,13 @@ public class PrettyPrinter {
   private func diagnose(_ message: Finding.Message, category: PrettyPrintFindingCategory) {
     // Add 1 since columns uses 1-based indices.
     let column = outputBuffer.column + 1
+    let converter = context.sourceLocationConverter
+    let absolutePosition = converter.position(ofLine: outputBuffer.lineNumber, column: column)
+    let sourceLocation = converter.location(for: absolutePosition)
     context.findingEmitter.emit(
       message,
       category: category,
-      location: Finding.Location(file: context.fileURL.path, line: outputBuffer.lineNumber, column: column)
+      location: Finding.Location(sourceLocation)
     )
   }
 }