Adds new option “pr-comment” for `automergeType` and a new option `automergeComment` to use in such a case.

Adds a link to the latest version notes in the PR body, as well as a source compare link for all commits between the current version and the new version.

Closes #1876

Closes #1661, Closes #1884, Closes #1909

Refactor changelog (commits) logic to separate sources, and remove the `changelog` dependency. Instead of a full copy/paste of commits, a link is now provided to the source repo.

Closes #381

This PR deprecates the use of `packageFiles` and migrates it to `includePaths` and `packageRules`.

Closes #1887

Adds a config option `includePaths` that allows the user to specify one or more paths to include in renovation and the rest will be excluded.