* freezer: implement split files for data

* freezer: add tests

* freezer: close old head-file when opening next

* freezer: fix truncation

* freezer: more testing around close/open

* rawdb/freezer: address review concerns

* freezer: fix minor review concerns

* freezer: fix remaining concerns + testcases around truncation

* freezer: docs

* freezer: implement multithreading

* core/rawdb: fix freezer nitpicks + change offsets to uint32

* freezer: preopen files, simplify lock constructs

* freezer: delete files during truncation

* core, eth, trie: bloom filter for trie node dedup during fast sync

* eth/downloader, trie: address review comments

* core, ethdb, trie: restart fast-sync bloom construction now and again

* eth/downloader: initialize fast sync bloom on startup

* eth: reenable eth/62 until we properly remove it

* typo fix

* change to stores

* core: lookup txs by block number instead of block hash

Transaction hashes now store a reference to their corresponding
block number as opposed to their hash. In benchmarks this was
shown to reduce storage by over 12 GB.

The main limitation of this approach is that transactions on
non-canonical blocks could never be looked up, however that is
currently not supported.

The database version has been upgraded to version 5 and the
transaction lookup process is backwards-compatible with the
prior two transaction lookup formats prexisting in the
database instance. Tests have been added to ensure this.

* core/rawdb: tiny review nit fixes

Solves #15210 without changing consensus, in a backwards compatible way,
by adding tx inclusion information to the Receipt struct.

This PR is a more advanced form of the dirty-to-clean cacher (#18995),
where we reuse previous database write batches as datasets to uncache,
saving a dirty-trie-iteration and a dirty-trie-rlp-reencoding per block.

* core: remove unnecessary fields in log

* core: bump blockchain database version

* core, les: remove unnecessary fields in txlookup

* eth: print db version explicitly

* core/rawdb: drop txlookup entry struct wrapper

* core, eth: fix database version

* eth: polish error message

* rawdb: remove unused parameter for WritePreimages func and modify a
spelling mistake

* rawdb: update the doc for function WritePreimages

* core/rawdb: use wrappered helper to assemble key

* core/rawdb: wrappered helper to assemble key

* core/rawdb: rewrite the wrapper, pass common.Hash

* all: get rid of error when create mdb

* core: clean up variables definition

* all: inline mdb definition