[OBS] - Investigate Amazon Application signals

[aatchison]

Application Signals can help us to express more elaborate SLI/SLOs for our obervability infrastructure.

Goals:

Determine if App Signals is a viable option for internal and external checks, combinations of indicators
Determine if IaC with pulumi is possible and robust.
Determine if these indicators can be rolled up to site24x7. Bonus points if we can leverage Pulumi IaC.