Add restart controller

[sbernauer]

Description

For stackabletech/issues#200
Actual implementation copied from https://github.com/stackabletech/restart-controller
Integration-Test: https://github.com/stackabletech/integration-tests/pull/207

Review Checklist

• Code contains useful comments
• (Integration-)Test cases added (or not applicable)
• Documentation added (or not applicable)
• Changelog updated (or not applicable)
• Cargo.toml only contains references to git tags (not specific commits or branches)
• Helm chart can be installed and deployed operator works (or not applicable)

Once the review is done, comment bors r+ (or bors merge) to merge. Further information

[maltesander]

Just some comments. Probably @teozkr needs to have another look :)

[nightkr]

LGTM for now, there's some documentation missing and generalization that we might want to do, but that's more of a problem that I need to get back to myself...

[sbernauer]

Thanks! Actually I intended to write some docs after this is merged. But for the generalization i think you're the best man!

[lfrancke]

Do we have a ticket for the documentation @sbernauer? If not, could you create one?

[sbernauer]

There is no dedicated ticket for docs but the docs are tracked as part of stackabletech/issues#200