* make service use both finalized and non-finalized state
* Document new functions
* add documentation to sled fns
* cleanup tip fn now that errors are gone
* rename height unwrap fn
## Motivation
While working on the block locator fix PR together with Henry we noticed that we'd accidentally serialized entire transactions in `tx_by_hash`, instead of serializing just the height of the block and the index of the transaction within the block, as described by the original RFC.
## Solution
We've fixed it by adding a `TransactionLocation` new type, which handles the sled format traits. We've removed the sled format impls for `Transaction` to prevent inserting the wrong data in the future. Finally we've bumped the database format to reflect the change in the format on the disk and its incompatibility with previous versions.
Jane Lusby
Deirdre Connolly
Jane Lusby