WIP: Update Dangerbot to accept a hide-changelog-warning flag
What does this MR do?
Dangerbot expects a changelog entry in the case of a feature flag, even though our documentation says a changelog entry should be added on removal of the flag.
Originally we considered adding the feature flag
label to the list of those that do not need a changelog entry, but since that label is applied both when an item is hidden behind a flag and when the flag is removed it would not trigger when necessary.
We could make a behind-ff
flag to deal with this case. OR we could add the ability to hide-chaneglog-warning
so we do not shoehorn cases into available flags or wind up with a list of 100 exceptions. With plenty of issue reviews, I don't expect this would be abused and we could even update the label summary to ask devs to add the reason they don't expect a flag to be necessary.