JS: Remove a dependency on getImportedPath()

To avoid negative recursion in some upcoming changes, we want to make sure the modeling of createRequire does not depend on getImportedPath().

javascript/ql/lib/semmle/javascript/ES2015Modules.qll

@@ -94,6 +94,11 @@ class ImportDeclaration extends Stmt, Import, @import_declaration {
 
   override PathExpr getImportedPath() { result = this.getChildExpr(-1) }
 
+  /**
+   * INTERNAL USE ONLY. DO NOT USE.
+   */
+  string getRawImportPath() { result = this.getChildExpr(-1).getStringValue() }
+
   /**
    * Gets the object literal passed as part of the `with` (or `assert`) clause in this import declaration.
    *