Fix timeout update example plugin

[ross-weir]

• Fix incompatibility with axios timeout config due to missing nodejs api shim, use signals instead
• Make example plugin do something with blockchain client
• Add file logging, added a sync version of rotating log handler, its the same as RotatingFileHandler provided by deno std log except uses *Sync methods. Closes Add file log handler #10 - it looks like this handler being async in deno might be a bug, we should hopefully be able to remove this handler at some point in the future: Log handler setup function is inconsistent denoland/std#3538 (comment)