* Remove logging from circuit breaker
The logging is never output, and if it was would be very verbose.
Instead of dropping the level down to trace the logger is removed
entirely.
* Add constants from trace library
The logging functionality in trace is being removed in an upcoming
release. To prepare the logging component keys are copied from trace
into teleport.
* Convert trace.ComponentFields to teleport.ComponentFields
* Replace trace.Component with teleport.ComponentKey
* Replace trace logging constants
* client-side upgrade window export
adds client-side logic for exporting maintenance windows
for external updaters. export behavior is enabled via
env var (`TELEPORT_EXT_UPGRADER=kube|unit`).
* print raw version
* update e-ref
Zac Bergquist