set_log_level should be consistent with run --verbose

[qrkourier]

Let set_log_level accept valid log level labels, rejecting invalid strings, or valid numbers, to be consistent with args to run --verbose option.

It currently respects only log level labels like INFO, but fails silently to set the level when the arg is like --loglevel 3 or --loglevel BOGUS.

We could add a usage hint to clarify the expected format of that arg like this.

[qrkourier]

❯ jq .LogLevel /var/lib/ziti/config.json
"debug"

❯ build/programs/ziti-edge-tunnel/Release/ziti-edge-tunnel set_log_level --loglevel 3
received response <{"Success":true,"Code":0}
>

❯ jq .LogLevel /var/lib/ziti/config.json                                             
"debug"

❯ build/programs/ziti-edge-tunnel/Release/ziti-edge-tunnel set_log_level --loglevel INFO
received response <{"Success":true,"Code":0}
>

❯ jq .LogLevel /var/lib/ziti/config.json                                                
"info"