merge: catch up with main (raw change streams PR #591)

Merges upstream main which includes PR #591 (raw change streams) and
PR #599 (direct BSON Buffer -> JSON conversion).

Auth fix conflicts (types.ts, config.test.ts) resolved — both sides
had the same fix, upstream also added database name decoding.

ChangeStream.ts has 11 unresolved conflicts — PR #591 replaced the
MongoDB driver ChangeStream with a custom RawChangeStream using raw
aggregate + getMore. Our Cosmos DB changes need to be re-applied to
the new code structure. Resolved in the next commit.

Author: Sleepful

.changeset/fluffy-carpets-repair.md

@@ -0,0 +1,5 @@
+---
+'@powersync/service-module-mongodb': minor
+---
+
+Use custom MongoDB change stream implementation to get better low-level control.