Improve the command line interface - parameters

[msm-code]

Suboptimal error messages and help:

❯ ./ursadb a
[2022-11-24 14:33:43.912] [info] UrsaDB v1.5.0+(unknown commit)
terminate called after throwing an instance of 'std::runtime_error'
  what():  Failed to open database file
fish: Job 1, './ursadb a' terminated by signal SIGABRT (Abort)

❯ ./ursadb --help
[2022-11-24 14:32:58.358] [info] UrsaDB v1.5.0+(unknown commit)
terminate called after throwing an instance of 'std::runtime_error'
  what():  Failed to open database file
fish: Job 1, './ursadb --help' terminated by signal SIGABRT (Abort)