In #3167 I removed the code that would use this, but forgot to remove the
exporting code. This follows up on that. We don't currently use this for
monitoring, and it's easier to get the current flags from a config file.
Updates #1699.
Adds a new package, `features`, which exposes methods to set and check if various internal features are enabled. The implementation uses global state to store the features so that services embedded in another service do not each require their own features map in order to check if something is enabled.
Requires a `boulder-tools` image update to include `golang.org/x/tools/cmd/stringer`.
Jacob Hoffman-Andrews
Roland Bracewell Shoemaker