Attempt to recover from in-process Supported Feature query failures.

Catch thrown exceptions and fallback to the previous mechanism of shelling out a `swift-frontend -emit-supported-features` task.
We are seeing spurious failures here and this will help potential users while we investigate the root cause.

Workaround for rdar://105559904

Author: artemcm

Sources/SwiftDriver/Jobs/EmitSupportedFeaturesJob.swift

@@ -64,9 +64,13 @@ extension Driver {
                                            fileSystem: FileSystem,
                                            executor: DriverExecutor)
   throws -> Set<String> {
-    if let supportedArgs =
-        try querySupportedCompilerArgsInProcess(of: toolchain, fileSystem: fileSystem) {
-      return supportedArgs
+    do {
+      if let supportedArgs =
+          try querySupportedCompilerArgsInProcess(of: toolchain, fileSystem: fileSystem) {
+        return supportedArgs
+      }
+    } catch {
+      diagnosticsEngine.emit(.warning_inprocess_supported_features_query_failed(error.localizedDescription))
     }
 
     // Fallback: Invoke `swift-frontend -emit-supported-features` and decode the output

Sources/SwiftDriver/Utilities/Diagnostics.swift

@@ -55,6 +55,10 @@ extension Diagnostic.Message {
     .warning("In-process target-info query failed (\(error)). Using fallback mechanism.")
   }
 
+  static func warning_inprocess_supported_features_query_failed(_ error: String) -> Diagnostic.Message {
+    .warning("In-process supported-compiler-features query failed (\(error)). Using fallback mechanism.")
+  }
+
   static func error_argument_not_allowed_with(arg: String, other: String) -> Diagnostic.Message {
     .error("argument '\(arg)' is not allowed with '\(other)'")
   }