This provides a machine-consumable way to get lint results as they occur. With the json-realtime option, each lint result is outputted on it's own line as "ugly" JSON, prefixed with an ##arc-lint## string.
Mostly this is to allow Harbormaster to parse lint results as they are run, rather than parsing all the results at the end.
As per D11690, the ##arc-lint## string is an identifier so we know what lines of output are lint results.