Closes #6357

Co-authored-by: Rhys Arkins <rhys@arkins.net>

This reverts commit f04adc50.

Ref #5555

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

This reverts commit b5c9dc8e.

feat: unify file locations

Adds undocumented/experimental “master issue” feature.

Setting `config.masterIssue = true` will result in Renovate opening and maintaining an issue that contains a list of all PRs both pending and open, and allowing some control over them (e.g. bypass schedule, force retry, etc).

Setting `config.masterIssueApproval` in addition will mean that branches are not created automatically and instead await approval in that master issue.

Closes #2595

Renovate will now put all its data in `path.join(os.tmpdir(), '/renovate’);` and will instruct npm and yarn to do the same. To force Renovate to use a specific folder, set `process.env.TMPDIR` when running. The previous variable `RENOVATE_TMPDIR` is now deprecated and will be rewritten to TMPDIR.

Closes #1794

Rewrite of dependency extraction, particularly for npm. Paves way for easier addition of new package managers.

Closes #1882