Deactivate maybeMap generation

[aloisdeniel]

Is your feature request related to a problem? Please describe

The maybeMap method from generated unions introduced a lot of issues in my recent projects. Union cases were added later on during development and were not processed in many places where maybeMap is used.

Describe the solution you'd like

I would like to deactivate the maybeMap method generation (with a build.yaml options?) to enforce all developers to process every state each time a new state is introduced in a union type.

Describe alternatives you've considered

We have considered adding a lint rule at the dev/CI level.

[realshovanshah]

Can we do the same for the copyWith method? @Lyokone would your help be possible in this too? I'll try to see if I can create a PR first.

[Lyokone]

Hey, the PR should be pretty similar to #565. Happy to help if needed. Not sure what would be the use case tho?

[realshovanshah]

I have filled an issue describing the my problem here: #587.
#576 also seemed to have a use case for this.