Support JS import attributes (previously import assertions)

Author: aibaars

javascript/extractor/src/com/semmle/jcorn/Parser.java

@@ -3563,7 +3563,9 @@ protected Statement parseImport(Position startLoc) {
   protected Expression parseImportOrExportAssertionAndSemicolon() {
     Expression result = null;
     if (!this.eagerlyTrySemicolon()) {
-      this.expectContextual("assert");
+      if (!this.eatContextual("assert")) {
+        this.expect(TokenType._with);
+      }
       result = this.parseObj(false, null);
       this.semicolon();
     }

javascript/extractor/tests/esnext/input/import-assertion.js

@@ -1,13 +1,13 @@
-import "module" assert { type: "json" };
-import * as v1 from "module" assert { type: "json" };
-import { v2 } from "module" assert { type: "json" };
-import v3 from "module" assert { type: "json" };
+import "module" with { type: "json" };
+import * as v1 from "module" with { type: "json" };
+import { v2 } from "module" with { type: "json" };
+import v3 from "module" with { type: "json" };
 
-export { v4 } from "module" assert { type: "json" };
-export * from "module" assert { type: "json" };
-export * as v5 from "module" assert { type: "json" };
+export { v4 } from "module" with { type: "json" };
+export * from "module" with { type: "json" };
+export * as v5 from "module" with { type: "json" };
 
-const v6 = import("module", { assert: { type: "json" } });
+const v6 = import("module", { with: { type: "json" } });
 
 import "module" // missing semicolon
 assert({type: "json"}); // function call, not import assertion