Support import fix/completions for export = (#25708)

src/compiler/checker.ts

@@ -2286,8 +2286,6 @@ namespace ts {
             return getPackagesSet().has(getTypesPackageName(packageName));
         }
 
-        // An external module with an 'export =' declaration resolves to the target of the 'export =' declaration,
-        // and an external module with no 'export =' declaration resolves to the module itself.
         function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol;
         function resolveExternalModuleSymbol(moduleSymbol: Symbol | undefined, dontResolveAlias?: boolean): Symbol | undefined;
         function resolveExternalModuleSymbol(moduleSymbol: Symbol, dontResolveAlias?: boolean): Symbol {

src/compiler/types.ts

@@ -3097,6 +3097,10 @@ namespace ts {
          */
         /* @internal */ getAccessibleSymbolChain(symbol: Symbol, enclosingDeclaration: Node | undefined, meaning: SymbolFlags, useOnlyExternalAliasing: boolean): Symbol[] | undefined;
         /* @internal */ getTypePredicateOfSignature(signature: Signature): TypePredicate;
+        /**
+         * An external module with an 'export =' declaration resolves to the target of the 'export =' declaration,
+         * and an external module with no 'export =' declaration resolves to the module itself.
+         */
         /* @internal */ resolveExternalModuleSymbol(symbol: Symbol): Symbol;
         /** @param node A location where we might consider accessing `this`. Not necessarily a ThisExpression. */
         /* @internal */ tryGetThisTypeAt(node: Node): Type | undefined;