* all: freezer style syncing
core, eth, les, light: clean up freezer relative APIs
core, eth, les, trie, ethdb, light: clean a bit
core, eth, les, light: add unit tests
core, light: rewrite setHead function
core, eth: fix downloader unit tests
core: add receipt chain insertion test
core: use constant instead of hardcoding table name
core: fix rollback
core: fix setHead
core/rawdb: remove canonical block first and then iterate side chain
core/rawdb, ethdb: add hasAncient interface
eth/downloader: calculate ancient limit via cht first
core, eth, ethdb: lots of fixes
* eth/downloader: print ancient disable log only for fast sync
* 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
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.
