indexeddb: Implement transaction support (fixes #1969)

[alexaustin007]

Implementing begin(), commit(), and rollback() methods in src/91indexeddb.js
Modifying CRUD operations (intoTable, fromTable, etc.) to use transactions when active
Adding fake indexeddb for Node.js testing environments
Creating test case test/test1969.js with commit/rollback verification
Updating dependencies in yarn.lock