Fetching logs by hash in blockchain database (#8463)

* Fetch logs by hash in blockchain database

* Fix tests

* Add unit test for branch block logs fetching

* Add docs that blocks must already be sorted

* Handle branch block cases properly

* typo: empty -> is_empty

* Remove return_empty_if_none by using a closure

* Use BTreeSet to avoid sorting again

* Move is_canon to BlockChain

* typo: pass value by reference

* Use loop and wrap inside blocks to simplify the code

Borrowed from https://github.com/paritytech/parity/pull/8463#discussion_r183453326

* typo: missed a comment