Revert "Add a new version of the communication protocol between DocC and external link resolver executables (#1292)" (#1299)

This reverts commit 9413c59.

Author: kavon

Sources/SwiftDocC/Checker/Checkers/AbstractContainsFormattedTextOnly.swift

@@ -1,7 +1,7 @@
 /*
  This source file is part of the Swift.org open source project
 
- Copyright (c) 2021-2025 Apple Inc. and the Swift project authors
+ Copyright (c) 2021 Apple Inc. and the Swift project authors
  Licensed under Apache License v2.0 with Runtime Library Exception
 
  See https://swift.org/LICENSE.txt for license information
@@ -14,7 +14,6 @@ public import Markdown
 /**
  A document's abstract may only contain formatted text. Images and links are not allowed.
  */
-@available(*, deprecated, message: "This check is no longer applicable. This deprecated API will be removed after 6.3 is released")
 public struct AbstractContainsFormattedTextOnly: Checker {
     public var problems: [Problem] = [Problem]()
     private var sourceFile: URL?

Sources/SwiftDocC/Infrastructure/DocumentationContext.swift

@@ -265,6 +265,7 @@ public class DocumentationContext {
     ///   - source: The location of the document.
     private func check(_ document: Document, at source: URL) {
         var checker = CompositeChecker([
+            AbstractContainsFormattedTextOnly(sourceFile: source).any(),
             DuplicateTopicsSections(sourceFile: source).any(),
             InvalidAdditionalTitle(sourceFile: source).any(),
             MissingAbstract(sourceFile: source).any(),
@@ -2738,17 +2739,17 @@ public class DocumentationContext {
         knownEntityValue(
             reference: reference,
             valueInLocalEntity: \.availableSourceLanguages,
-            valueInExternalEntity: \.availableLanguages
+            valueInExternalEntity: \.sourceLanguages
         )
     }
 
     /// Returns whether the given reference corresponds to a symbol.
     func isSymbol(reference: ResolvedTopicReference) -> Bool {
         knownEntityValue(
             reference: reference,
-            valueInLocalEntity: \.kind,
-            valueInExternalEntity: \.kind
-        ).isSymbol
+            valueInLocalEntity: { node in node.kind.isSymbol },
+            valueInExternalEntity: { entity in entity.topicRenderReference.kind == .symbol }
+        )
     }
 
     // MARK: - Relationship queries