Configuration options for hardcoded values

[nstogner]

• Add MESSENGER_ERROR_MAX_BACKOFF config env var
• Add AUTOSCALING_TIME_WINDOW config env var
• Add AUTOSCALING_INTERVAL config env var

For time window calc see: https://go.dev/play/p/b2GdRzMJPUb

[nstogner]

Fixes #109

[nstogner]

Fixes #108

[samos123]

Is setting MESSENGER_ERROR_MAX_BACKOFF=0s the same as turning of the backoff? Would that work?

[nstogner]

Yep, that should disable