Feature request: use config from dependabot.yml

[timstibbs-hippo]

Use case: my dependabot.yml config isn't doing quite what I expected, so I'd love to be able to run that locally against my local branch to test out the effect of different config options.

I suspect that the job.yaml file can do everything that you can do in dependabot.yml, however the two are different. This prevents you using this CLI to build your dependabot.yml file. If we could support fetching config from dependabot.yml, then you'd be able to use the same file both locally and on github.

To illustrate this, I'm imagining running the following command:

dependabot update <ecosystem> dummy/repo --local . --config .github/dependabot.yml

Even better if it could pick up that file automatically, but I realise this might be challenging from a backwards compatibility perspective.

Note that I don't have a good understanding of the differences of the capabilities of job.yaml vs dependabot.yml, so this suggestion might essentially be impossible.

Note also that this is related to, but not the same as: #59. Would also potentially satisfy dependabot/dependabot-core#4605.

[joshnoe]

I'd assume this is by far the most common use-case for running dependabot locally: checking why your dependabot.yml file isn't working.

I'm not sure there's much purpose of this tool without this support? Are we supposed to create job.yml files that are "best guesses" of what would be represented in a dependabot.yml file?