feat(engine): adds body character count

[sajithneyo]

This PR adds a character count feedback when typing the body.

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So by showing the count a rough idea can be taken when typing the commit message about where to end the line break "\n" without letting commitlint to do it automatically and also gives a basic idea about the body character count. Additionally a config "maxBodyLineWidth" can be set to show line length in the prompt reminding other developers about the line lengths configured. It defaults to 80.

If this is not suitable for the current release, please add this feature in the next release. This helped me a lot to manage and plan my commit messages nicely.

[ThisIsMissEm]

I don't think you need another configuration option here, just using maxLineWidth should be okay. The automatic wrapping actually happens in cz-conventional-commit: https://github.com/commitizen/cz-conventional-changelog/blob/master/engine.js#L206

[sajithneyo]

@ThisIsMissEm updated the PR