Refactor tests so that resources can be created late
OpsLoggerFactory creates resources late
Mention StackTraceProcessor in OpsLoggerFactoryTest
Add simple error handling to BasicOpsLogger via a Consumer

Add a default error handler that prints the throwable to
System.err.
Code cleanup
OpsLoggerFactory configures StackTraceProcessors

Configuration is currently implicit, and not customisable.

* Logging to a PrintStream uses a SimpleStackTraceProcessor.
* Logging to a Path uses a FileSystemStackTraceProcessor
configured to store stack traces as siblings of the path used
for the log file.

To support this, BasicOpsLogger now has a more general
dependency (on StackTraceProcessor), instead of depending
on SimpleStackTraceProcessor.
Code cleanup
Code cleanup
Explicit OpsLoggerFactory support for StackTraceProcessors

OpsLoggerFactory can now explicitly create and configure
StackTraceProcessing for a BasicOpsLogger.

* Stack traces can be saved to a custom path
* Logging to a file without storing stack traces in a separate
file is supported
* Stack traces can be stored in files when logging to a generic
PrintStream such as System.err.
Add missing unit test
Code cleanup
Code cleanup

Introduce optional
Code cleanup
Code cleanup
Code cleanup

Clarify the logic for determining the path to store stack traces.