Draft: Add backtraces to all exceptions (#18159) - 2nd attempt
This supersedes: !3236 (closed)
Submodules / Libraries
- Pretty printing of backtraces
- Adjust / add Haddock (especially, add the changes from the proposal.)
- General clean up (Formatting, remove left-overs, etc.)
- Figure out how to upstream changes on submodules. (That's mostly a chicken-and-egg problem.)
I.e. the implementation of the core functionality - as described by the proposal - is done. But, to finally merge it, the open issues should be resolved.