Add structured logger

[nishkrishnan]

This is two changes:

• Replacing all usages of SimpleLogger with it's interface SimpleLogging which makes it easier to swap out loggers going forward
• Nukes SimpleLogger in favor of StructuredLogger which allows us to better analyze logs in our log management system we choose.

Right now the real changes are scopped to simple_logger.go and logging_test the rest of the changes are just interface changes + test changes to support the new constructor for NoopLogger

Note: As a base logger I'm using zap

[msarvar]

Are we planning on upstreaming this? I worry that replacing simple logging will cause issues to other atlantis users. If they have some sort of log parser that relies on current non structured format.

[msarvar]

great job!

[nishkrishnan]

Are we planning on upstreaming this? I worry that replacing simple logging will cause issues to other atlantis users. If they have some sort of log parser that relies on current non structured format.

Yeah but I'd argue this is objectively way better than what exists and can be coupled with a major release. Parsing the existing format seems like a nightmare and the existing format doesn't play nice with any log ingestion system.

Though this is a good callout for sure. Maybe it could be wise to add a server flag to basically fork between structured logging and simple logging but seems like a lot of work right now for our usecase, we can discuss it in the upstream PR.