Support grouping dependency updates in PRs

[lukaszwawrzyk]

By default we create and maintain 1 PR per version update.
We should allow users to customize this, for example grouping updates of specific dependencies together, minor/patch updates in one PR, etc.
Scala Steward has it well made.

[jastice]

In Scala steward and dependabot this feature is very helpful in reducing PR spam distractions and associated commits for usually insignificant updates. I usually configure my projects to have a single monthly update. Would be nice to have it for Bazel steward for sure.

[lukaszwawrzyk]

@jastice You could already configure Bazel Steward to for example group all maven updates into one PR, but it would be update each time Bazel Steward runs.

Anyway, I'd recommend switching to Renovate (https://docs.renovatebot.com). Bazel Steward has some advantages, but I Renovate is much more mature and feature rich. It now supports bzlmod and maven dependencies which originally was an advantage of Bazel Steward, but is not anymore.
It is based on text parsing though, it doesn't run bazel to extract information, but if you keep your BUILD predictable, it is going to work.

If for any reason you think that Bazel Steward does significantly better job than Renovate, please let me know, maybe there is an important reason to invest into maintaining it.

[jastice]

I see, thank you! I wasn't up to date in the tooling in this area