feat: initial support for case type selection

[espoal]

Summary

This is the first of a multi PR effort aiming at supporting custom name casing conventions, as detailed here.

1. This PR attempts to update @nestjs/schematics to accept a caseType option when generating a controller.
2. In this PR we add a caseNaming field to GenerateOptions
3. This is the PR to document the new option
4. Future PRs will extend this feature in term of supported actions, tests and configuration

For now I decided to support only controllers, to reduce the changes size and make reviewing easier. If the approach will be approved I will make sure to extend it to other objects and to add more tests. For the reviewer please check this in particular.

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Other... Please describe:

What is the current behavior?

Currently @nestjs/cli uses kebab-or-snake case, as mentioned in this issue.

What is the new behavior?

The goal is to add a caseNaming option to nest-cli.json so that generated files will follow the desired name casing convention.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other informations

[benjGam]

Hi, maybe i missed something, but this shouldn't be pascal by default ?

[espoal]

In the original implementation a case named kebab-or-snake is used, which is the snake you see referred here. I kept the original default to avoid unintended side effects, for example other piece of the nestjs codebase default to and expect snake as input, or they will complain