query cycles could be handled more like ICEs

from https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/recent-ish.20nightly.20regression.20wrt.20Freeze

Sometimes the compiler blurps out something like error[E0391]: cycle detected when XYZ

yay: the compiler saved itself from going in circles infinitely because it noticed it was trying to compute something self-referential

nay: we SHOULD have had a proper diagnostic earlier in which the compiler errors out and explains the user why the self-referential thing they are trying to do is not going to work out instead of just throwing a "oops, query cycle" in their face.

If we encounter such a query cycle, we should tell users to report it a diagnostic bug.
Maybe we can also improve the spans of the E0391 a bit.

error[E0391]: cycle detected when looking up late bound vars
 --> /home/matthias/vcs/github/rust_misc_stuff/tests/ui/traits/inheritance/auxiliary/icemaker_omni/BE190CEE104A225CD4B33CFB5FA41C069766D54BE3319CDCF10B5BCBEC24AD11.rs:4:1
  |
4 | pub trait MyNum : Add<Output=Self> + MyNum<Output=Self> + Mul<Output=Self> + PartialEq + Clone {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
note: ...which requires resolving lifetimes...
 --> /home/matthias/vcs/github/rust_misc_stuff/tests/ui/traits/inheritance/auxiliary/icemaker_omni/BE190CEE104A225CD4B33CFB5FA41C069766D54BE3319CDCF10B5BCBEC24AD11.rs:4:1
  |
4 | pub trait MyNum : Add<Output=Self> + MyNum<Output=Self> + Mul<Output=Self> + PartialEq + Clone {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...which requires computing the super traits of `MyNum` with associated type name `Output`...
 --> /home/matthias/vcs/github/rust_misc_stuff/tests/ui/traits/inheritance/auxiliary/icemaker_omni/BE190CEE104A225CD4B33CFB5FA41C069766D54BE3319CDCF10B5BCBEC24AD11.rs:4:1
  |
4 | pub trait MyNum : Add<Output=Self> + MyNum<Output=Self> + Mul<Output=Self> + PartialEq + Clone {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  = note: ...which again requires looking up late bound vars, completing the cycle
note: cycle used when computing the super predicates of `MyNum`
 --> /home/matthias/vcs/github/rust_misc_stuff/tests/ui/traits/inheritance/auxiliary/icemaker_omni/BE190CEE104A225CD4B33CFB5FA41C069766D54BE3319CDCF10B5BCBEC24AD11.rs:4:1
  |
4 | pub trait MyNum : Add<Output=Self> + MyNum<Output=Self> + Mul<Output=Self> + PartialEq + Clone {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information

error: aborting due to 3 previous errors

Start with the query and queries sections of the Rust compiler development documentation linked in the issue, then reproduce the shown E0391 cycle involving MyNum. Determine how cycle diagnostics should distinguish compiler bugs from user errors and whether their spans can be improved. Done means the cycle produces a more actionable diagnostic, or explicitly directs users to report a diagnostic bug, with improved spans where possible.