Allow parsing of "nonisolated" as a type specifier along with "isolated"

This is used for isolated conformances.

Author: DougGregor

Sources/SwiftParser/generated/Parser+TokenSpecSet.swift

@@ -3503,6 +3503,7 @@ extension SimpleTypeSpecifierSyntax {
     case __shared
     case __owned
     case isolated
+    case nonisolated
     case _const
     case borrowing
     case consuming
@@ -3518,6 +3519,8 @@ extension SimpleTypeSpecifierSyntax {
         self = .__owned
       case TokenSpec(.isolated):
         self = .isolated
+      case TokenSpec(.nonisolated):
+        self = .nonisolated
       case TokenSpec(._const):
         self = ._const
       case TokenSpec(.borrowing):
@@ -3541,6 +3544,8 @@ extension SimpleTypeSpecifierSyntax {
         self = .__owned
       case TokenSpec(.isolated):
         self = .isolated
+      case TokenSpec(.nonisolated):
+        self = .nonisolated
       case TokenSpec(._const):
         self = ._const
       case TokenSpec(.borrowing):
@@ -3564,6 +3569,8 @@ extension SimpleTypeSpecifierSyntax {
         return .keyword(.__owned)
       case .isolated:
         return .keyword(.isolated)
+      case .nonisolated:
+        return .keyword(.nonisolated)
       case ._const:
         return .keyword(._const)
       case .borrowing:
@@ -3589,6 +3596,8 @@ extension SimpleTypeSpecifierSyntax {
         return .keyword(.__owned)
       case .isolated:
         return .keyword(.isolated)
+      case .nonisolated:
+        return .keyword(.nonisolated)
       case ._const:
         return .keyword(._const)
       case .borrowing:

Tests/SwiftParserTest/DeclarationTests.swift

@@ -765,6 +765,15 @@ final class DeclarationTests: ParserTestCase {
     )
   }
 
+  func testParseIsolatedConformances() {
+    assertParse(
+      """
+      extension Int: @MainActor P {}
+      extension Int: nonisolated Q {}
+      """
+    )
+  }
+
   func testParseDynamicReplacement() {
     assertParse(
       """