* add prune ancient feature
* change notes and log for pr suggest
* change StableStateBloc to SafePointBlock and enhanced 'pruneancient' flag hints
* change pruneancient usage
* fix note misspelling
* fix set SafePointBlockNumber by mpt height replace current block number
Co-authored-by: user <joeycli0919@qq.com>
This change introduces garbage collection for the light client. Historical
chain data is deleted periodically. If you want to disable the GC, use
the --light.nopruning flag.