add silent and verbose log option

[JyJyJcr]

with option -s or --silent, log nothing.
with option -v or --verbose, log debug message.
now -s option enables to remove the two line errors at exit as below:

log4rs: Broken pipe (os error 32)
log4rs: Broken pipe (os error 32)

these errors were caused by sending log messages to the pipe between ssh client (as stdout) when it is already closed.

[oowl]

Actually, I would prefer to use env_logger to achieve it. https://docs.rs/env_logger/latest/env_logger/

[JyJyJcr]

env_logger seems great for log level control, but it cannot output into file but stdout or stderr. If you not care for the log_file option --log, I'll replace log4rs to env_logger.

[oowl]

env_logger seems great for log level control, but it cannot output into file but stdout or stderr. If you not care for the log_file option --log, I'll replace log4rs to env_logger.

Yeah, it can accept not using log4rs.

[JyJyJcr]

switched to env_logger. timestamp format slightly changed.

log4rs:

2024-01-31T23:45:26.791057+09:00 INFO quicssh_rs::client - [client] Connecting to <addr>

env_logger:

[2024-01-31T14:46:01Z INFO  quicssh_rs::client] [client] Connecting to <addr>

[oowl]

Thanks!

[oowl]

@JyJyJcr we also need to update README doc https://github.com/oowl/quicssh-rs?tab=readme-ov-file#usage, Can you help me update it?

[JyJyJcr]

OK, I continue to use this branch to update README/Usage.
pull-requesting from this branch inevitably contains duplicated commits, so I requested from another branch.