Persister for IndexDB

[nicoburniske]

Changes

• Add impl for indexed_db using https://github.com/Alorel/rust-indexed-db
• Gated behind indexed_db feature
• Add ?Send to QueryPersister async trait
  • By adding ?Send to the async_trait macro, it indicates that the futures produced by the trait methods do not have to be Send, which is fine because everything is single threaded.

Indexdb connection is eagerly initialized using AsyncCell. All operations will await the connection being initialized (and the database created if need be)`. DB name and Object store name are customizable

In testing,

• db setup takes 50ms
• retrievals take between 3-10ms (probably averaging around 5ms) for a small database.

Misc Changes

• Breakup persister module into separate files (local_storage, index_db)
• Added cargo.lock to examples/start_axum which was being ignored for some reason