Remove legacy libSyntax related options

`-emit-syntax` and `-verify-syntax-tree` are not supported anymore.

Author: rintaro

Sources/SwiftDriver/Driver/Driver.swift

@@ -1901,7 +1901,7 @@ extension Driver {
       case .indexFile:
         compilerOutputType = .indexData
 
-      case .parse, .resolveImports, .typecheck, .dumpParse, .emitSyntax,
+      case .parse, .resolveImports, .typecheck, .dumpParse,
            .printAst, .dumpTypeRefinementContexts, .dumpScopeMaps,
            .dumpInterfaceHash, .dumpTypeInfo, .verifyDebugInfo:
         compilerOutputType = nil

Sources/SwiftOptions/Options.swift

@@ -293,7 +293,6 @@ extension Option {
   public static let emitSupportedFeatures: Option = Option("-emit-supported-features", .flag, attributes: [.frontend, .noInteractive, .doesNotAffectIncrementalBuild], helpText: "Emit a JSON file including all supported compiler features", group: .modes)
   public static let emitSymbolGraphDir: Option = Option("-emit-symbol-graph-dir", .separate, attributes: [.helpHidden, .frontend, .noInteractive, .argumentIsPath, .supplementaryOutput], metaVar: "<dir>", helpText: "Emit a symbol graph to directory <dir>")
   public static let emitSymbolGraph: Option = Option("-emit-symbol-graph", .flag, attributes: [.helpHidden, .frontend, .noInteractive, .supplementaryOutput], helpText: "Emit a symbol graph")
-  public static let emitSyntax: Option = Option("-emit-syntax", .flag, attributes: [.helpHidden, .frontend, .noDriver], helpText: "Parse input file(s) and emit the Syntax tree(s) as JSON", group: .modes)
   public static let emitTbdPathEQ: Option = Option("-emit-tbd-path=", .joined, alias: Option.emitTbdPath, attributes: [.frontend, .noInteractive, .argumentIsPath, .supplementaryOutput])
   public static let emitTbdPath: Option = Option("-emit-tbd-path", .separate, attributes: [.frontend, .noInteractive, .argumentIsPath, .supplementaryOutput], metaVar: "<path>", helpText: "Emit the TBD file to <path>")
   public static let emitTbd: Option = Option("-emit-tbd", .flag, attributes: [.frontend, .noInteractive, .supplementaryOutput], helpText: "Emit a TBD file")
@@ -693,7 +692,6 @@ extension Option {
   public static let verifyGenericSignatures: Option = Option("-verify-generic-signatures", .separate, attributes: [.frontend, .noDriver], metaVar: "<module-name>", helpText: "Verify the generic signatures in the given module")
   public static let verifyIgnoreUnknown: Option = Option("-verify-ignore-unknown", .flag, attributes: [.frontend, .noDriver], helpText: "Allow diagnostics for '<unknown>' location in verify mode")
   public static let verifyIncrementalDependencies: Option = Option("-verify-incremental-dependencies", .flag, attributes: [.helpHidden, .frontend], helpText: "Enable the dependency verifier for each frontend job")
-  public static let verifySyntaxTree: Option = Option("-verify-syntax-tree", .flag, attributes: [.frontend, .noDriver], helpText: "Verify that no unknown nodes exist in the libSyntax tree")
   public static let verifyTypeLayout: Option = Option("-verify-type-layout", .joinedOrSeparate, attributes: [.helpHidden, .frontend, .noDriver], metaVar: "<type>", helpText: "Verify compile-time and runtime type layout information for type")
   public static let verify: Option = Option("-verify", .flag, attributes: [.frontend, .noDriver], helpText: "Verify diagnostics against expected-{error|warning|note} annotations")
   public static let version: Option = Option("-version", .flag, attributes: [.frontend], helpText: "Print version information and exit")
@@ -1012,7 +1010,6 @@ extension Option {
       Option.emitSupportedFeatures,
       Option.emitSymbolGraphDir,
       Option.emitSymbolGraph,
-      Option.emitSyntax,
       Option.emitTbdPathEQ,
       Option.emitTbdPath,
       Option.emitTbd,
@@ -1412,7 +1409,6 @@ extension Option {
       Option.verifyGenericSignatures,
       Option.verifyIgnoreUnknown,
       Option.verifyIncrementalDependencies,
-      Option.verifySyntaxTree,
       Option.verifyTypeLayout,
       Option.verify,
       Option.version,