ci: Implement a local commit linter using Husky

[virkt25]

Currently commitlint is configured to run on Travis. It is possible to configure it to run commitlint locally using Husky by tying into the commithook. This will allow developers to know if their commit message is valid when they write it instead of waiting to figure out once Travis is done running.

We would still keep the Travis check as an enforcement but this will make developer / contributor experience for @loopback more pleasant.

[dhmlau]

@virkt25 , as discussed, this can be a core GA item. thanks.

[kjdelisle]

@dhmlau @Raymond I think we should do this sooner. Waiting on remote CI to validate my commit messages is a very large time sink and handling it before it gets pushed to a PR is a must, IMO.

[dhmlau]

Agree that we need commit linter to be run locally, not waiting for CI to fail just because of the commit message. :)
I'll leave the choice of using Husky (or other alternatives) to the team.