melos package manager support

[rarkins]

Discussed in https://github.com/renovatebot/renovate/discussions/25956

^{Originally posted by **spydon** November 24, 2023} ### Tell us more. # Feature description Many Dart and Flutter projects use [Melos](https://github.com/invertase/melos) to handle their monorepos and from version [3.2.0](https://github.com/invertase/melos/pull/526) Melos supports specifying [shared dependencies](https://melos.invertase.dev/commands/bootstrap#shared-dependencies) in the `melos.yaml` file. These dependencies are specified in the same manner as in the `pubspec.yaml` file except that they are a subsection of the `bootstrap` section, so it should be fairly trivial to re-use the already existing code for updating the normal `pubspec.yaml` files. Example of a file with such shared dependencies: https://github.com/flame-engine/flame/blob/main/melos.yaml#L16-L25

[github-actions[bot]]

Hi there,

You're asking us to support a new package manager. We need to know some basic information about this package manager first. Please copy/paste the new package manager questionnaire, and fill it out in full.

Once the questionnaire is filled out we'll decide if we want to support this new manager.

Good luck,

The Renovate team

[rarkins]

See https://github.com/renovatebot/renovate/discussions/25956#discussioncomment-7681869