JS-545 Configure renovate to use repox private npm registry

[zglicz]

JS-545

As we noticed, renovate uses the public npm registry. Let us update this to first look in repox as the registry!
@jayadeep-km-sonarsource @hedinasr (I found your names as you've either previously touched this config or added a new source - https://sonarsource.atlassian.net/browse/BUILD-5885 ) - 2 questions:

1. how can I test this?
2. should this be added in the parent configs of renovate? I see that for maven we already have this in a common setup - https://github.com/SonarSource/renovate-config/blob/master/default.json#L22
   Could this come preconfigured for npm to use repox? As example see this pull request and the package-lock.json file -
   https://github.com/SonarSource/SonarJS/pull/5233/files
   We change all of the urls from repox to the public repository.

[zglicz]

this was weirdly indented, moving to top level

[sonarqube-next]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[zglicz]

@hedinasr or @jayadeep-km-sonarsource - do you have any pointers/suggestions?

[jayadeep-km-sonarsource]

Hi @zglicz ,
Changes looks good to me. I suggest you merge this and test it here. You can login to renovate, trigger the run and check the logs to validate if it is working as expected.
Moving this to renovate-config repo seems like a good idea. We will have to discuss internally and make sure that it will work with all the teams using it. I can bring it up to our squad discussion once you validate the changes in this repo.

[zglicz]

@jayadeep-km-sonarsource Therefore, could you approve? I'm alone on the team for this week :)