Feat: allow modification of log message formatting?

[reinkrul]

In our system, we want to mask certain data to make sure we don't accidentally log PII (Personally identifiable information), like social security numbers. A central place to do this would be our logger, but zerolog's Msgf function doesn't allow alteration of its behavior. For example, configuring a custom message formatting function.

What do you think of such a feature, and would you be willing to accept a PR for it (if it meets the criteria obviously)?