fix(mongodb-build-info): add back missing default export (#588)

Currently published versions of mongosh fail to install via `npm`
because the typescript migration in c6ad0b0 removed the ability
to consume this package through its default export.

While I am generally strongly in favor of avoiding default exports,
this particular change was an unintentional breaking change that
should have been labeled as such.

Let's bring back the prior behavior for now and remove separately
as an intentional breaking change.

Author: addaleax

packages/mongodb-build-info/src/index.ts

@@ -235,3 +235,16 @@ export function getBuildEnv(buildInfo: unknown): {
         : null,
   };
 }
+
+/** @deprecated */
+export default {
+  getDataLake,
+  isEnterprise,
+  isAtlas,
+  isAtlasStream,
+  isLocalhost,
+  isDigitalOcean,
+  getGenuineMongoDB,
+  identifyServerName,
+  getBuildEnv,
+};