Force one line logs via env

[timkelty]

Makes it possible to force one line logs, even if dev mode is enabled.

Implemented as CRAFT_LOG_ALLOW_LINE_BREAKS, (to match MonologTarget::allowLineBreaks) but open to suggestions:

CRAFT_SINGLE_LINE_LOGS=1
CRAFT_ONE_LINE_LOG=1
CRAFT_LOG_LINE_BREAKS=0
CRAFT_SINGLE_LINE_LOGGING=1

EDIT: I'm actually reconsidering if we actually need this…if I can use the Composer autoload event, I might be able to DI our Dispatcher in time to change MonologTarget::allowLineBreaks in cloud. @brandonkelly thoughts?

[bencroker]

Just noticed this and wanted to give you a heads-up. I could of course have overlooked something.