[ref] duniter-dbs: move dbs def in module databases

rust-bins/duniter-dbex/src/main.rs

rust-bins/duniter-dbex/src/migrate.rs

rust-libs/duniter-dbs-read-ops/src/lib.rs

rust-libs/duniter-dbs-write-ops/src/bc.rs

rust-libs/duniter-dbs-write-ops/src/bc/identities.rs

rust-libs/duniter-dbs-write-ops/src/bc/txs.rs

rust-libs/duniter-dbs-write-ops/src/bc/uds.rs

rust-libs/duniter-dbs-write-ops/src/lib.rs

rust-libs/duniter-dbs-write-ops/src/txs_mp.rs

rust-libs/duniter-dbs/src/databases.rs

rust-libs/duniter-dbs/src/databases/bc_v1.rs

rust-libs/duniter-dbs/src/databases/bc_v2.rs

rust-libs/duniter-dbs/src/databases/cm_v1.rs

rust-libs/duniter-dbs/src/databases/gva_v1.rs

rust-libs/duniter-dbs/src/databases/txs_mp_v2.rs

rust-libs/duniter-dbs/src/lib.rs

rust-libs/duniter-dbs/src/open_dbs.rs

rust-libs/duniter-dbs/tests/test_explorer.rs

rust-libs/duniter-dbs/tests/test_read_write.rs

rust-libs/duniter-mempools/src/lib.rs