feat(changelog): allow to pass a custom context

[dnlup]

In repositories that are self-hosted most of the time the changelog is genereated with broken links that are missing the owner and the repository in the path.
Allowing to pass a custom context to conventionalChangelog mitigates this.

See issue #525 and #227.

.versionrc.js example configuration

module.exports = {
//...
context: {
  owner: 'some repo owner',
  repository: 'foo'
}

---

I saw #174 after opening this, sorry.

[coveralls]

Coverage increased (+0.01%) to 99.442% when pulling 76bb460 on dnlup:feat/context into 2f04ac8 on conventional-changelog:master.

[dnlup]

I am trying to figure out why the test fails on Windows. It will take a bit since I have to setup an environment for that. Any feedback is greatly appreciated in the meantime 🙏.

[dnlup]

Maybe this work is not needed, I just saw #204 (comment).

[dnlup]

Since I opened this PR, I found alternative solutions for the problems I thought it would have solved. I still think there is value in adding this feature, but for now, I don't have the time to work on it. So I will close this to avoid unnecessary noise and come back later.