Work out how to manage labels

Currently ghc/ghc> has nearly 100 labels. These fall into a variety of categories:

1. Labels that classify the ticket (~bug, ~"feature request", ~task)
2. Labels that classify bugs by their manifestation: compiler perf, compiler crash, ghc build failure
3. Labels that specify the environmental conditions under which an issue will manifest:
   • architectures: ARM, SPARC, PowerPC
   • operating system: Windows, macOS
4. Labels that specify which compiler or program features are implicated in a bug
   • language extensions: ImpredicativeTypes, StaticPointers, UnboxedTuples
   • program constructs: join points, ~"levity polymorphism", STM
   • compiler feature: recompilation checking, cpp, debug information, cross-compilation
5. Labels that specify which bit of implementation a bug is likely caused by:
   • compiler subsystem: driver, simplifier, demand analysis, RTS, LLVM backend
   • related GHC project: ghc-pkg, integer-simple, nofib, core libraries, infrastructure
   • external project: haddock, hadrian
6. Labels that specify other attributes of a ticket: newcomer, ~"backport request", info needed, ~"user facing"

It's not clear which of these are useful, which are just noise, and how we should best group them.

We have two tools for logically grouping labels:

• prefixing the label name with some sort of category string
• color