Add grouped updates

[anym0us]

Our company is migrating to Dependabot from another similar tool (Depfu).

One of the features we miss is grouped updates (when all available updates are merged into 1 PR). Here's how the option is configured for every repository in Depfu's settings (just for example):

[greysteil]

Thanks for the feedback @anym0us. We love the Depfu folks and I was really sad we were in competition with them.

We don't have support for grouped updates yet, so if that's a feature you really need I recommend you stick with Depfu for now. We'll get there on it, but it's just not the way Dependabot currently works.

[frangio]

I'm really interested in this feature to reduce the number of Dependabot PRs. I see that the PR was pinned a month ago. Would it possible to clarify whether this is in the roadmap? Thanks!

[tuan-bui]

We're interested in this feature as it makes it a lot easier to view it all in one PR. Wondering when it is planned for release also, cheers!

[JeremyTX]

We're also interested in this feature. If there are any estimates, it would be much appreciated!

[RichiCoder1]

PR simplicity + less notification noise + less Github Actions minutes spent processing dep PRs :)

[rbright]

Beyond reduction of PR noise and build cost, grouping would be valuable for libraries that need to be updated together for purposes of compatibility.

For example, updating a single AWS CDK package can lead to test failures due to API compatibilities with other CDK packages. Upgrading them all at once generally mitigates this issue.

Until update grouping is possible, we have to disable CDK auto-updates and apply them manually.

[mbrevda]

Same for react + react-dom - these always need to be updated in tandem.