Fix get grop mempool with unknown chain
[*] Fix. Now function dap_chain_net_get_gdb_group_mempool_by_chain_type if unknown chain then returns the name group cdb, example 'gdb_group_prefix.mempool' but not NULL.
This merge request to branch develop
[*] Fix. Now function dap_chain_net_get_gdb_group_mempool_by_chain_type if unknown chain then returns the name group cdb, example 'gdb_group_prefix.mempool' but not NULL.
This merge request to branch develop