[ref] bc-db-writer: isolate CURRENT_META_DATAS update

lib/modules/blockchain/bc-db-writer/src/blocks.rs

...modules/blockchain/bc-db-writer/src/current_meta_datas.rs

lib/modules/blockchain/bc-db-writer/src/lib.rs

lib/modules/blockchain/bc-db-writer/src/writers/requests.rs

lib/modules/blockchain/blockchain/src/fork/fork_algo.rs

lib/tests-tools/bc-db-tests-tools/src/mocks.rs