Need user defined typeMap

This file [typeDisplayNames.ts](https://github.com/arvinxx/gitmoji-commit-workflow/blob/6a4789836b4cbc34a19ccd805e6dd5c7f7c4a4ee/packages/changelog/src/transformer/typeDisplayName.ts) defines an object typeMap that is used by getDisplayName.

It'd be great if a user-defined typeMap can be supported by the configuration file, Let me know if I can raise a PR for this. 