refactor: move logger to monorepo

packages/logger/README.md

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+# @openstapps/logger
+
+[![pipeline status](https://gitlab.com/openstapps/logger/badges/master/pipeline.svg)](https://gitlab.com/openstapps/logger/commits/master)
+[![coverage report](https://gitlab.com/openstapps/logger/badges/master/coverage.svg)](https://gitlab.com/openstapps/logger/commits/master)
+
+This is a simple logger for TypeScript projects with transformations for the log output.
+
+Logs are only printed if their log level is equal or higher than the defined log level.
+
+## Log Levels
+
+Available log levels are:
+- 1 - INFO
+- 2 - LOG
+- 4 - WARN
+- 8 - ERROR
+- 16 - OK
+
+You can set your log level with the environment variable `STAPPS_LOG_LEVEL`.
+
+To select your desired log levels add the corresponding numbers and set the value of `STAPPS_LOG_LEVEL` to the sum.
+
+For example `STAPPS_LOG_LEVEL=17` is 16 + 1 and would log everything that is `OK` or `INFO`.
+
+If you want to use logger in production (`NODE_ENV=production`) and allow all transports to fail set `ALLOW_NO_TRANSPORT` to `true`.
+
+Additionally setting the environment variable `STAPPS_EXIT_LEVEL` which works in the same manner as `STAPPS_LOG_LEVEL` will terminate your process after logging at the selected level(s) (usefull for integration tests). It will be ignored in afore mentioned productive environments.
+
+## SMTP
+
+This class also provides a simple implementation of an SMTP transport which can be used as a
+`TransportWithVerification` for the logger. You can use this to transport errors of the logger or to transport mails
+of your own monitoring solution.
+
+### Usage
+
+You can instatiate it with a config or it will check for a config in the environment variables. Environment variables
+can overwrite the actual config values.
+
+Environment variables are:
+
+* SMTP_AUTH_USER:      SMTP username
+* SMTP_AUTH_PASSWORD:  SMTP password
+* SMTP_HOST:           SMTP host
+* SMTP_PORT:           SMTP port
+* SMTP_RECIPIENTS:     comma seperated list of recipients
+* SMTP_CC:             comma seperated list of recipients for the carbon copy (CC)
+* SMTP_SENDER_MAIL:    sender of the mail
+* SMTP_SENDER_NAME:    name of the sender
+* SMTP_SECURE:         `true` to enable tls
+
+## Transformations
+
+By default the logger will only add the log level to the message. It will replace newlines with spaces and might skip some of your choosen Transformers when in production (`NODE_ENV=production`) for compatibility reasons with existing log aggregators and analyzers.
+
+You can change this behavior by setting other Transformers via `Logger.setTransformations`. If you do so, mind the order of the transformers.
+
+You may choose from the following:
+
+* `AddLogLevel`, which prepends the output with the log level
+* `Colorize`, which colorizes the output according to the log level
+* `Timestamp`, which prepends a timestamp to the output