Closes #10230

Co-authored-by: Michael Kriese <michael.kriese@visualon.de>

Adds an extra migration step after resolving config in order to migrate nested presets.

Closes #8579

This reverts commit b5c9dc8e.

Added support for `renovate.json5` filename. Now configuration can be parsed from a `json5` format file.

Closes #3484 

- Refactor: move fixtures to corresponding directories
- Delete unused fixtures

Resolves: #3328 

Changes the way Renovate treats renovate config inside `package.json` files. Before, config used to be applied only to that particular file, meaning that it was not applied for the rest of a monorepo, or for other package managers like Docker. Now, any `renovate` section inside the repository’s root `package.json` will be applied globally, just the sams as if it were contained within a `renovate.json` file. This means there is no longer any case where you *must* have a `renovate.json` file instead of `package.json`.

Closes #1323

BREAKING CHANGE: renovate config in `./package.json` is now applied to whole repository, and renovate config inside non-root `package.json` files is now ignored.

This PR updates Renovate to detect config validation problems and (1) stop processing, and (2) either raise an Issue if already onboarded, or (2) update the onboarding PR to reflect the error if still onboarding.

Closes #1300 

Renovate will now check for `renovate.json`, `.renovaterc`, and `.renovaterc.json` in that order. JSON-only supported (no YAML).

Closes #969

Remove original getFile, getFileContent, and getFileJson and replace with getFile (which used to be getFileContent.. shortened now for convenience). Also remove unused getSubdirectories functions.

Repository logic code has been rearranged for better logic and file separation.

Closes #654