chore(export-to-language): replace usage of vm module COMPASS-7312 (#4967)

Author: addaleax

package-lock.json

@@ -80,6 +80,7 @@
     "chai": "^4.3.6",
     "compass-preferences-model": "^2.15.1",
     "depcheck": "^1.4.1",
+    "ejson-shell-parser": "^1.2.4",
     "enzyme": "^3.11.0",
     "eslint": "^7.25.0",
     "hadron-app-registry": "^9.0.11",

packages/compass-export-to-language/package.json

@@ -0,0 +1,9 @@
+import parseShellBSON, { ParseMode } from 'ejson-shell-parser';
+
+export function countAggregationStagesInString(source: string): number {
+  const parsed = parseShellBSON(source, { mode: ParseMode.Loose });
+  if (!Array.isArray(parsed)) {
+    throw new Error('Source expression is not an aggregation stage array');
+  }
+  return parsed.length;
+}