Fix a miscompile when a test function has a raw identifier parameter label. (#1168)

Resolves #1167.

### Checklist:

- [x] Code and documentation should follow the style of the [Style
Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md).
- [x] If public symbols are renamed or modified, DocC references should
be updated.

Author: grynspan

Sources/TestingMacros/TestDeclarationMacro.swift

@@ -160,6 +160,8 @@ public struct TestDeclarationMacro: PeerMacro, Sendable {
       for (label, parameter) in parametersWithLabels {
         if parameter.firstName.tokenKind == .wildcard {
           LabeledExprSyntax(expression: label)
+        } else if let rawIdentifier = parameter.firstName.rawIdentifier {
+          LabeledExprSyntax(label: "`\(rawIdentifier)`", expression: label)
         } else {
           LabeledExprSyntax(label: parameter.firstName.textWithoutBackticks, expression: label)
         }

Tests/TestingTests/MiscellaneousTests.swift

@@ -315,6 +315,11 @@ struct MiscellaneousTests {
     let displayName = try #require(suite.displayName)
     #expect(displayName == "Suite With De Facto Display Name")
   }
+
+  @Test(arguments: [0])
+  func `Test with raw identifier and raw identifier parameter labels can compile`(`argument name` i: Int) {
+    #expect(i == 0)
+  }
 #endif
 
   @Test("Free functions are runnable")