feat(manager/sbt): support proxy registries

[lpriyasivakumar]

Changes

Sbt builds allow for proxy/mirror registries to be defined in a repositories file. This PR is to add this feature to renovate

Context

Currently, the default maven repository is always used to pull dependencies in a sbt project.
Registry overrides are not supported.

Sbt looks for a launcher configuration file with the following entries:

• -Dsbt.override.build.repos=true
• -Dsbt.repository.config=

Based on the provided location, the repositories file is parsed to get the repositories for plugins and build dependencies.

Default scala repositories: Link

[repositories]
  local
  typesafe-ivy-releases: https://repo.typesafe.com/typesafe/ivy-releases/, [organization]/[module]/[revision]/[type]s/[artifact](-[classifier]).[ext], bootOnly
  maven-central
  sonatype-snapshots: https://oss.sonatype.org/content/repositories/snapshots

Example scala repositories file: Link

[repositories] 
  local 
  my-ivy-proxy-releases: http://repo.company.com/ivy-releases/, [organization]/[module]/(scala_[scalaVersion]/) (sbt_[sbtVersion]/)[revision]/[type]s/[artifact](-[classifier]).[ext]
  my-maven-proxy-releases: http://repo.company.com/maven-releases/ 

Test repository: https://github.com/lpriyasivakumar/lila-fishnet/tree/test-branch

Documentation (please check one with an [x])

• I have updated the documentation, or
• No documentation update is required

How I've tested my work (please select one)

I have verified these changes via:

• Code inspection only, or
• Newly added/modified unit tests, or
• No unit tests but ran on a real repository, or
• Both unit tests + ran on a real repository

[secustor]

First pass 🙂

[viceice]

we know registry urls is defined

[renovate-release]

🎉 This PR is included in version 37.217.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)
• 37.217.0

Your semantic-release bot 📦🚀