Add commitlint to check commit messages

[tsagadar]

Implements commitlint as proposed in #110.

Opted to use rule set "@commitlint/config-conventional". This should implement (in my understanding) https://www.conventionalcommits.org/en/v1.0.0/ .

Note: this differs to our previous rules in the following way

1. Mandates to use a type prefix
2. Mandates to write lower-case description

@easybe what do you think of https://www.conventionalcommits.org

[b-rowan]

Looked at the spec, seems like a good change 👍

[easybe]

I am not a fan. I don't see the point in using semantic commit messages unless you deduce versions from them. As previously stated, I like the style used by projects like the Linux kernel or Git itself (https://cbea.ms/git-commit/). Look at the format used by Git for e.g. revert commits, why fight the tool on that?

[tsagadar]

So let's stick to what we have. Closing PR and will close #110 as well.