Ability to log to stderr **by default**

[gkc]

Is your feature request related to a problem? Please describe.

Recently we added the ability to specific a different output handler for AtSignLogger. However, this must be set for each AtSignLogger constructed. This means it is not possible to make all AtSignLoggers used by your program send their log to stderr - since most of the loggers are created in dependent libraries

Describe the solution you'd like

• Make a static method on AtSignLogger to allow setting of a default log output handler
• modify AtSignLogger constructor to allow nulls for the output handler, and if null then use the current static default

Describe alternatives you've considered

No response

Additional context

No response