Implement escaping #2

Similar to https://druid.apache.org/docs/latest/configuration/#configuration-interpolation

If you need to set a variable that is wrapped by ${...} but do not want it to be interpolated, you can escape it by adding another $. For example:

config.name=$${value}

Actually you can already do stuff such as config.name=${value} without problems, as long as you don't use config.name=${env:dont-replace. But this is IMHO low prio