Consider config reload on SIGHUP

[alexvanin]

It will be nice to reload and update app on the go.

Reload whole app

The easiest way is to restart application and therefore re-read config. This is acceptable but we don't want to close all connections and terminate all sessions. So consider more innocent approach

Reload some config sections

• 🔴 Update wallet: key is used in the client, not sure we can safely re-read that
• 🟢 Restart pprof + metrics servers
• 🟢 Update logger config
• 🟡 Update cert files: if possible without server termination
• 🔴 Update NeoFS peers: pretty sure it is not possible. Consider weight update feature issue in SDK.
• 🟡 Update buffer sizes: if possible without server termination
• 🟢 Update resolve order
• 🔴 Update pool timers: pretty sure it is not possible. Consider feature issue in SDK.
• 🟢 Timestamp header parameter
• 🟢 Enable / disable compression

Check if all 🟢 sections are re-readable.
Investigate 🟡 sections
Discuss if 🔴 sections are mandatory to update without restart /cc @realloc