[Spec] Add support for the new breaking change "bang"

[byCedric]

Expected Behavior

In the latest version of the conventional commits (1.0.0-beta.4) a new feature is added to define "breaking changes". It's still in beta but already released as specification-feature. This means we could add some new rules to validate this. We also have to update our type rules to make them play nice with this I guess.

conventional-commits/conventionalcommits.org#134

Possible implementations

We can modify the type-enum rule to only allow trailing ! in this rule, or we can modify @commitlint/ensure to let it pass too. I prefer the first one because e.g. scopes should not have this functionality right?

Current Behavior

Affected packages

• cli
• core
• prompt
• config-angular

Possible Solution

Steps to Reproduce (for bugs)

Context

Your Environment

[byCedric]

Closed in favor of #658